350 SUMMARY OF CURRENT RESEARCHES RELATING TO 



has a definite organization, which appears at the same stages in all the 

 animals studied. In the case of chromosome pair A it was possible to 

 trace this through all stages from the spermatogonia to the spermatids, 

 thus constituting a demonstration of a case of continuous identity or 

 individuality through these stages. 2. Conjugation takes place by 

 parasynapsis. The paper is arranged under convenient headings, and a 

 good bibliography is appended ; it is illustrated by a series of nine plates 

 (121 figures) of camera-lucida drawings, and one containing nine photo- 

 micrographs. These are good and elucidate the author's views. 



J. A. T. 



)3. Onychophora. 



Early Development of Peripatus capensis. — Editk H. Glen 

 {Quart. Journ. Micr. Sci., 1919, 63, 283-92, 1 pi.). A revision of 

 material does not confirm the late Adam Sedgwick's view that in the 

 early stages there are no cell limits. Undoubted cell walls can be 

 seen both in ectoderm and in endoderm. By a cell wall is here meant 

 a layer of non-protoplasmic substance which is formed as a secretion, 

 and which separates the cells from one another. The difficulty in seeing 

 them is due to the large size and extremely irregular shape of the cells, 

 and to the numerous vacuoles in the endoderm cells. According to 

 Sedgwick the whole of the nephridium is mesodermic. This is not 

 confirmed, for the whole tube is ectodermic except the funnel, which is 

 mesodermic. The nephridium of Peripatus is not a coelomiduct, but 

 homologous with the true nephridium of worms. J. A. T. 



S. Arachnida. 



A Hundred New Mites.— A. Berlese {Redia, 1918, 13, 115-92), 

 An account is given of a fourth century of new Acarina from Zululand, 

 Polynesia, Mexico, Brazil and other parts of the world. J. A. T. 



Heart of Limulus. — S. Nukada {MT. Med. Fak. K. Univ. Tohyo, 

 1917, 19, 1-104, 21 pis.). There is in Limulus the beginning of 

 an auricle which beats in rhythmic harmony with the part corre- 

 sponding to 'the ventricle. The minute structure of the wall of both 

 parts is described at length. The stimulation and co-ordination is 

 purely nervous ; the muscle fibres do not assist. The automotor centres 

 or stimulating ganglion-cells are not in permanent activity ; the stimuli 

 pass rhythmically to the heart muscle. Inhibitory and motor nerves 

 regulate the activity of the heart as in Vertebrates. Indeed there is no 

 essential difference between the activity of the Limulus heart and that 

 of Vertebrates. But we cannot do more than call attention to this 

 important physiological investigation. J. A. T. 



f. Crustacea. 



Abnormality in Australian Crayfish. — Janet W. Eaff {Proc. 

 Roy. Soc. Victoria, 1919, 31, 325-6, 1 pi.). A male of Parachseraps 

 hicarinatus Gray showed the right eye slightly larger and longer in the 



