SUMMARY OF CURRENT RESEARCHES. 419 



a chemical substance which, in combination with the ovian cytoplasm, 

 produces the body in question." " Such a view," Prof. Farmer says,* 

 " would reconcile much that has hitherto been difficult of explanation 

 in connection with the diverse behaviour of centroaomes in different 

 organisms, and even in different cells and tissues of the same indi- 

 vidual." 



Nature of Fertilisation.-]-— E. Hertwig has made numerous cultures 

 of Adinosphserium in order to get more secure data in regard to " plasto- 

 gamy"or fusion of cytoplasm apart from fusion of nuclei (" Karyo- 

 gamy"). 



In Actinosphserium the process occurs in quite definite conditions, — 

 at the close of intense nutritive periods and also at times when the 

 power of assimilation has ceased. It occurs when there is disproportion 

 between nucleoplasm and cytoplasm. Forms appear which are the 

 results of the plastogamy of perhaps a hundred units, and may be re- 

 cognised, apart from their large size, by the fact that the different 

 regions of the giant show different phases of nuclear change. 



There is a causal relation between the ordinary vital functions and 

 the occurrence of natural death. In opposition to Weistnann, it is 

 maintained that natural death is the necessary consequence of life. The 

 Protozoa must come to an end like the Metazna, but there are processes 

 which counteract the injurious influences of long-continued life. The 

 most effective counteractive is fertilisation, " a process in which, from 

 the material of two units gradually verging towards destruction, a new 

 vitally energetic individual is formed." 



Grand-parental Inheritance.! — N. Blanchard contributes an article 

 on grand-parental inheritance, collecting all known data and supple- 

 menting them by the coefficients for grandsires in the case of coat- 

 colour for thoroughbred horses. He emphasises the need for further 

 work on " blending," as distinguished from "alternative" inheritance, 

 and suggests the need for experiments on the grand-parental relation 

 in small mammals or insects. 



Numerical Law of the Germ-Cells.§ — J. Beard states in particular 

 reference to his studies on the early development of skate-embryos 

 (Raja batis) and dog-fish embryos (Scyllium canicula), the following 

 law: — "The number of primary germ-cells in any given Metazoan 

 development is 2", but with the sacrifice, entailed by the development 

 of one primary germ-cell to form an embryo for the reception of the 

 rest, the greatest actual number of primary germ-cells in any embryo 

 will be 2" — 1 . " One would need to be very sure of one's methods to 

 contradict this 1 



Spermatogenesis in Phalangista vulpina.|| — K. von Korff de- 

 scribes the four periods in the development of the spermatozoa of this 

 Marsupial. 



The sperm-nucleus is flattened into an oval body lying transverse 



* Nature, lxvi. (1902) p. 74. 



t SB. Ak. AViss. Munchen (Math.-Phys. Classe), 1902, Heft i. pp. 57-73. 



J Biometrika, i. (1902) pa 361-4. 



§ Anut. Anzeig.. xxi. (1902) pp. 189-200. 



|| Arch. Mikr. Anat., lx. (1902) pp. 232-60 (2 pis. and 4 figs.). 



