210 SUMMARY OF CURRENT RESEARCHES RELATING TO 



in the active division of the " foot-cell," which, is perhaps a kind of 

 nutrient organ for the seminiferous elements, if these lose their 

 cell-individuality by the metamorphosis of their nucleus. The active 

 life of the " foot-cell " is spoken to by the retraction of its processes. 

 This will alone explain the protrusion of the conical pole of the 

 seminal cells towards the wall of the tubule. 



Ovary of Echidna.* — Mr, F. E. Beddard gives a short sketch of 

 previous papers on this subject, and after mentioning Mr. Poulton's f 

 observations on the ovum of Ornitliorhynchus in greater detail, gives his 

 own results, with figures, of work on the ovary of Echidna. 



He summarizes these results, which agree in the main with 

 Poulton's, as follows : — (1) the follicular epithelium remains as a 

 single layer of cells round the ovum, till it leaves the Graafian follicle, 

 as is the case with lower Yertebrata ; (2) the ovum completely fills 

 the follicle ; (3) the ovum is very much larger than in other mammals ; 

 (4) the ovum is invested only by the vitelline membrane, which 

 becomes very thin or atrophies on maturity ; (5) the ovum consists of 

 a central mass of yolk, surrounded by a finer granular layer ; (6) the 

 nucleus lies excentrically, just below the peripheral layer of proto- 

 plasm. 



Influence of Shocks on the Germs of the Fowl's Egg.^ — 



M. C. Dareste has made some observations on the contradictory results 

 obtained in some experiments on the eggs of fowls. He directs again 

 attention to what he calls the individuality of the germ, which is the 

 dominant fact in teratogeny ; this will explain why some embryos are 

 normal and others monstrous, after having been submitted to the same 

 shocks. The nature and mode of action of the shocks is also an 

 important element, and they affect the egg differently according to its 

 position. In other words, experiments may be largely varied. He 

 has operated with an instrument which gives 1620 shocks a minute, 

 and he has thus been able to give from 24,800 to 97,200 shocks; as 

 a result he finds that the number of shocks is of no influence ; an 

 effect once produced is not increased by further action. On the other 

 hand it is quite possible to alter the position of the eggs acted on, and 

 this has been found to be of very great importance. Eggs affected 

 when the position of the long axis was vertical and the more acute 

 pole superior, generally gave rise to monstrous forms, while when 

 the axis was turned upside down, or set transversely, the embryos 

 were ordinarily normal, and in some cases chicks appeared. 



Peptone in Hens' Eggs during Incubation.§ — Dr. W. Fischel, 

 as the result of the examination of forty-two eggs at various periods 

 of incubation (2Dd to 19th day), found peptones in eight cases, both in 

 the embryonic tissues and in the yolk, in one embryo as much as 

 54 mgrm. being present. Peptones were never found before the 

 15th day, and in some cases not even after that date. 



* Pioc. E. Pliys. Soc. Edinburgh, 1885, pp. 354-62. 



. t Quart. Joum. Micr. Sci., xxiv. (1884) pp. 118-28 (1 pi.). 



j Comptes Renrlus, ci. (1885) pp. 834-6. 



§ Zeitschr. f. Physiol. Chem., x. (1885) pp. 11-3. 



