770 SUMMARY OF CURRENT RESEARCHES RELATING TO 



where there are more than two ova in one follicle, the same pheno- 

 menon obtains, one only continuing its further development. About 

 this time the ovary lies free in the perigastric cavity. 



Soon the yolk of the eggs becomes darker and granular, and 

 frequently so contracts that a peripheral space is left between it and 

 the egg-wall ; as the nutrient material is used up, the central portion 

 of the follicle gradually becomes clearer and thinner, and by the 

 absorption of the cells a passage is left for the egg. The free 

 egg is rounded or oval, and. is generally of some size; its passage 

 into the brood-capsule is probably effected by muscular contractions. 

 The author comes to the conclusion that fertilization does not take 

 place in, but externally to the ovicells. Hermaphrodite zooecia were 

 rarely observed ; but when they were, the arrangements were such as 

 to point to self-fertilization. The eggs would seem to be developed 

 independently of the polypides. 



The testes appear to be developed later than the ovaries, and not 

 at a definite point of the zocecium ; they are irregular in form, and 

 consist of masses or cords of rounded darkly-pi gmented cells, very 

 similar in appearance to those of the primitive ovaries ; the male 

 zocecia are less numerous than the female. 



The author thinks that there can be no doubt that the Bryozoa have 

 a general phylogenetic relation to the Eotifera, Mollusca, Ckaetopoda, 

 and Grephyrea (the Trochosphere-larva, Balfour) ; in their oogenesis 

 they have most marked resemblance to the Cheetopoda and Gephyrea. 



Arthropoda. 



Brain of Crustacea and Insects.* — J. Bellonci, in an account of 

 the nervous system of Sphceroma serratum, whose brain appears to be 

 intermediate between that of Decapod Crustacea and that of Insects, 

 insists on what Berger and Claus have already shown, viz. that the 

 lateral enlargements of the brain of the higher Crustacea are not, as 

 Dietl supposed, the optic lobes, but that the optic ganglion is the true 

 optic centre and altogether corresponds to the optic lobes of insects. 

 In fact, in SpJicerorna, as in Nephrops, the lateral swellings of the 

 median cerebral segments are the centres of origin for delicate fibrils 

 which belong to the antennary (interior) nerves, and they correspond, 

 both in relation and structure, to the antennary swellings of the brain 

 of insects. So again, in Crustacea just as in Insects, the fibres from 

 the optic lobes penetrate between tbese swellings and the superior 

 lobes : and, if we consider that the swellings of the nerve of the 

 external antennas are formations peculiar to the Crustacea, we see that 

 in them the lobes containing the olfactory " glomeruli " have just the 

 same relations to the oesophageal commissure as the same parts in 

 insects. The parts which, in the Crustacea, are really homologous 

 with the fungiform bodies of insects are the internal lobes of the 

 superior cerebral segment. 



The author supports his views by an account of the structure of the 

 brain of Gryllotalpa ; at the same time he recognizes the marked 



* Arch. Ital. de Biol., i. (1882) pp. 176-92. 



