esis in several species of Stenobothrus that the chromosomes of the spermatocytes are made up of rods, sometimes 2 and sometimes. 4. The length of these rods varies in arithmetic progression. In each of 4 species studied there are 5 short chromosomes, no two of which are the same length; altho the 5 short chromosomes in one species correspond with the 5 short ones of the others. There are also 3 larger chromosomes in each species, but these long chromosomes do not belong in the different species to the same numerical series. The author believes that the external specific differences between the species are dependent on the differences in the long chromosomes, altho he is unable to establish the correlation between. the rod-lengths and the body characteristics. SPERMATOGENESIS IN HYBRID PIGEONS Smith (Quart. J. Mic. Sci. 1912, p. 159) reports studies of the sperm formation and structure in the hybrids formed by mating a male pigeon and female domestic dove, and compares these with the condition in pure breeds. In the first maturation division in the hybrids the chromosomes do not unite to form 8 bivalent chromosomes but occur quite irregularly about the spindle and are finally distributed to the poles. irregularly. The second maturation division is practically suppressed. The secondary spermatocytes proceed at once to form spermatids and spermatozoa. Many of these are on the average twice the normal size, altho otherwise apparently normal structurally. In other cases there were structural abnormalities. It is known experimentally that hybrids of these stocks are infertile, and it seems that the sterility may be due to the inability of the specifically different chromosomes to unite in the normal synapse, with the consequent disturbance in the whole maturation process. MALE GERM CELLS IN NOTONECTA Browne (Jour. Exp. Zool. Jan. 1913) discusses the differences in form and number of the chromosomes in three species of Notonecta. She finds that the differences in the chromosome condition may be explained in these species by the relations of two particular chromosomes. In N. undulata the two chromosomes in question are always separate; in N. irrorata are always united to form a single body; and in N. insulata they may be separated in the first spermatocyte division, but are united in the second. The author traces the origin of the chromosomes from the karyosphere in the three species, and their behavior in the growth stages and maturation divisions. INTERSTITIAL CELLS OF TESTIS AND SECONDARY SEX CHARACTERS J. des Cilleuls (C. R. Soc. Biol. Paris, 1912, p. 371) finds a strict coincidence in the development of the interstitial cells of the testis and the secondary sexual characteristics of the cock. In chickens the external marks of sex do not begin to appear until about the thirtieth day. By the time the chicks are 45 days old the pullets show a greater development of the tail feathers and the cockerel more color and size of comb. The sex distinctions increase from this point. The author claims that the secondary sex characters in the male bird begin to show with the oncoming of the interstitial cells, and increase as these increase. The author believes that the secretion of the interstitial cells acts as a hormone in stimulating the growth of the characteristic male secondary structures. MICROBIOLOGY IN RELATION TO DOMESTIC ANIMALS This book, entitled "Principles of Microbiology," with a subtitle "A Treatise on Bacteria, Fungi, and Protozoa Pathogenic for Domesticated Animals," is written primarily for veterinary students beginning the study of microbiology. It consists, in about equal parts, of matter belonging to general bacteriology and to special applications of this to veterinary science. In the very nature of the case this makes the treatment of general bacteriology somewhat less satisfactory than may be had from text-books on this subject, and limits the author somewhat in his treatment of the part of the subject which is peculiar to the book. The first twelve chapters are given to such subjects as the biology, morphology, classification of bacteria; the apparatus, methods of sterilization, cultivation, staining, and examination of bacteria; the relation of bacteria to disease. In the part relating to the work of the veterinarian there are, first, two introductory chapters dealing with the Use of Animals in Bacteriological Examinations and Investigations, and the Bacteriology of Water and Milk. These are followed by eight chapters dealing with the various principal genera and species of microorganisms that produce diseases in domestic animals, together with their pathogenesis and, where known, the treatment. These chapters present very valuable material for the general student of biology, as well as for the veterinarian. In the concluding chapters the author discusses some of the broader questions of physiology, theory, diagnosis and therapy of the bacterial diseases under the heads:-Specific Bacterial Products, Tissue Reactions and Immunity; Serum Diagnosis; Immunity and Vaccine Therapy. This resumè is very readable and valuable to the general student. The mechanical excellence of the book is all that could be desired. Principles of Microbiology, by V. A. Moore. Pages 506; illustrated. Carpenter & Co., Ithaca, N. Y. Price $3.50. BEGINNERS GUIDE TO THE MICROSCOPE This is an elementary handbook designed to aid the untechnical person to use the microscope for his own pleasure and that of his friends. The need of such a book seems to the author to lie in the great complexity of the modern instrument and the wealth of its accessories, and in the elaborate character of the modern books about the microscope. In a very simple, gossipy way quite suitable to his expressed purpose, the author describes the microscope and its essential parts, the formation of images, illumination; discusses the principles that should guide in the choice of an instrument; gives rules for the use of the instrument and for its care; tells of interesting objects for temporary mounts. There are also sections on the home aquarium, on collecting objects, on mounting for permanent display, and on storing slides. In many ways it is much to be regretted that there are not more of our modern Americans who turn to such methods of interest and diversion as are suggested here. The use of the microscope as a serious instrument of education and research in schools has in creased greatly in this country; but it is remarkable that so few people use it as a means of recreation, pleasure, and general culture. The Beginners Guide to the Microscope, by Chas. E. Heath, F. R. M. S. Illustrated; 120 pages. Price 1 shilling. Percival Marshall & Co., London. MICROSCOPY AND DRUG EXAMINATION In this little book the author seeks to present in a simple and condensed form the elements of microscopy and histology demanded by pharmaceutical students. In Part I, which is given to Microscopy, are discussed briefly, often too briefly to be satisfactory,microscopes, microscopic photography, manipulation and care of the microscope, reproduction and measurements of microscopic objects; histology, microchemistry; the preparation and mounting of microscopic objects; cells; plant and animal tissues; microscopy of starches, etc. A series of laboratory exercises illustrating certain part of plant and animal biology follow. Part II is taken up with suggestions as to the microscopical examination of some 35 "drugs" in their commercial form. In Appendix A is a valuable table defining the various elements constituting and produced by cells, giving their properties and the method of identifying them by staining or otherwise. The last 50 pages of the book are given to figures illustrating lenses, microscopes, drawing apparatus, tissues, organs, drugs. Mechanically the book is marred by the unnecessarily large type in which the words desired to be emphasized are printed. Microscopy and the Microscopical Examination of Drugs, by Charles E. Gabel, Ph.D., Microscopical Food and Drug Analyst Iowa State Dairy and Food Commission. Illustrated; 114 pages. Price $1.00, postpaid. Des Moines, Iowa. |