ZOOLOGY AND BOTANY, MICROSCOPY, ETC. ' 569 



a reduced cell. The reduction is accomplished in two distinct stages 

 of development ; first affecting the spermatomcres, and then the sper- 

 matogems. While each spermatocyte intervenes in the formation of 

 a cytophor, the residual corpuscles are formed by the spermatomeres, 

 in such a way that not only each spermatocyte (and, therefore, each 

 spermatozoon), but also each sperraatogon only possesses a reduced 

 nucleus. 



Spermatogenesis in Ascaris megalocephala.*— P. Hallez, like 

 E. van Beneden, has selected this convenient Nematode for the study 

 of the phenomena of spermatogenesis. After a short description of 

 the male organs, he points out that young of different ages as well as 

 mature specimens must be examined. The spermatospores, which are 

 formed at the blind end of the seminal tube, consist of a homogeneous 

 extremely transparent protoplasm ; by division into four the nucleus 

 gives rise to four protospermatoblasts, which form protospermatogems. 

 The former give rise to a (second) generation of deutospermatogems, 

 which are formed by a large number of deutospermatoblasts. The 

 last become isolated, and consist of a homogeneous protoplasm and a 

 nucleus which is deeply stained by reagents. As they increase in 

 size their protoplasm becomes finely, then more distinctly granular, 

 while the nucleus grows larger and developes a nucleolus. 



When they have reached a size of about 18 yu, in diameter they 

 divide by nuclear division ; and this division is effected at about 

 440 mm. from the blind end of the seminal tube. 



The deutospermatoblasts now become filled with refractive 

 granules, and soon exhibit a phenomenon which has not yet been 

 observed in the animal kingdom. They undergo conjugation by 

 pairs, and the two become closely united with one another. Tho 

 nuclei, after fusion, separate afresh. As they tend to separate from 

 one another each gives rise to corpuscles, which resemble polar 

 globules. 



The further development of the separated and ejaculated deuto- 

 spermatoblasts must be made out in the organs of the female ; when 

 they first enter the ducts they are spherical cells, 18 or 19 fx in 

 diameter, their protoplasm is filled with refractive granules, and they 

 have a nucleus which can be easily stained. After a certain time tho 

 refractive or nutrient granules disappear, and the deutosiicrniato- 

 blasts appear almost to be amoeboid in character. They are now con- 

 verted into spermatozoa, which are ordinarily conical or pyramidal in 

 form ; the nucleus is constantly found outside the spermatozoon. 

 The fertilizing element is now ripe and may be seen to apply itself 

 to and fecundate an ovum. 



Nematoids of Sheep's Lungs.f— F. Karsch has a notice of A. Koch's 

 essay on the Nematodes of sheep's lungs, in which esi)ecial attention 

 has been given to Strongylus rufescens and its developmental history. 

 The author found in tlic lungs of a Hungarian race of sheep a 

 number of hair- like microscopic parasites wliicli lie regarded as new 



* Bull. Sci. Dep. Nonl, vi. (188.3) pp. 182 5. 

 t Biol. Contrail)!., iv. (IS.S4j jip. r,l-•^. 

 S*-!-. 2 — Vni.. IV. O ,, 



