ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 165 



where the middle piece disappears. He adduces evidence of the forma- 

 tion of the definitive centrosome de novo from the sperm nucleus. The 

 paper includes a critique of current theories of fertilisation, and also an 

 account of experiments designed to throw light on the nature of the 

 physical processes involved in these phenomena. 



Dermoid Cysts of Ovary and Testis.* — S. G. Shattock discusses 

 the origin and significance of these growths ; describing in particular a 

 remarkable specimen from a human subject which contained two in- 

 formed lower limbs between which there was a vulva, and behind the 

 latter a median perineal raphe. Above the vulva there grew a tuft of 

 long pubic hair, whilst the rest of the teratoma was covered with lanugo 

 only. At the base of the mass was a smooth cavity in which there lay a 

 blind coil of intestine. In each of the lower limbs there was an 

 elongated compound skeletal element, and in the trunk a rudimentary 

 spinal column and pelvic girdle. On one side there was a rudimentary 

 upper limb. Medullated nerve tissue was demonstrated in the spinal 

 cord. The author reviews and rejects the hitherto proposed theories of 

 such cysts, substituting one which he terms " epigenesis." He suggests 

 that the ovarian teratomatous cyst resulted from the fertilisation of a 

 primordial ovum in the embryo, so that the embryo furnished a second 

 imperfect individual, the origin of which was not therefore synchronous 

 with, but later than itself. It is not necessary to suppose that a second 

 penetration of the developing ovum by spermatozoa took place. It is 

 well-known that more than a single spermatozoon may perforate the 

 investing membrane of the ovum, and one might fertilise a primordial 

 ovum, which is assumed to be early formed. This theory involves the 

 preliminary maturation of the ovum at an abnormally early date. 

 Further, in the case of such cysts in the testicle, the assumption has to 

 be made that the gonad in question contained primordial ova — was, in 

 fact, an ovo-testis. 



Secretions of the Genital Organs.f — G. Loisel, in a second paper, 

 continues his account of the phenomena of secretion of the genital 

 organs. The present paper deals with the absorption of unlaid ova 

 (spurious corpora lutea), the function of the interstitial cells, the 

 chemical products elaborated in the ovary, and the toxic qualities of the 

 ovary compared with that of other tissues. In general, it may be 

 stated that the ovary fulfils a purifying function in the organism. This 

 consists in fixing, transforming, or destroying certain injurious products 

 poured into the blood by the somatic tissues and brought to the ovary 

 by the arterial system. The elements which treat these products are, 

 in invertebrates, the ova and follicular cells ; in vertebrates, the corpus 

 luteum and interstitial cells. Some of the products are purely and 

 simply excreted, others are thrown out along with the ova and utilised 

 in sexual reproduction, while others are reabsorbed by the organism as 

 internal secretions. 



Absorption of Yolk in Viper Embryos.! — H. Dubuisson has en- 



* Brit. Med. Journ., No. 2288 (1904) pp. 1248-9. 

 + Journ. de l'Anat. et Phys., xli. (1905) pp. 5S-93. 

 % Comptea Bend us, exxxix. (1904) pp. 684-6. 



