ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 41 



ventrally, and the ninth and tenth are fused. The end of the ahdomen 

 bears the lamime abdominales, between which lie the genital and anal 

 apertures in a groove. Except in Tineola the two openings are however 

 distinct from one another. In relation to the laminae abdominales, thero 

 are two pairs of chitinous rods — the apophyses. The ovaries, as in 

 Lepidoptera in general, consist of four ovarian tubes. The common 

 oviduct of each side opens into the vestibulura, which again opens into 

 the vagina. The vestibulum receives the common ductus sebaceus of 

 the paired sebaceous glands, and also the canalis vestibuli of the recepta- 

 culurn seminis. This organ consists of a glandular tube, the glandula 

 receptaculi, and the lagena receptaculi, or receptacle proper, from which 

 leads the canalis receptaculi, which becomes the canalis spiralis before 

 passing into the canalis vestibuli. The bursa copulatrix consists of a 

 spacious sac and a narrowed neck (cervix) ; it communicates with the 

 vestibule by a tube called the ductus seminalis. Full details of all these 

 organs are given for the forms studied by the author. 



Determination of Sex in Lepidoptera.* — Prof. A. Giard calls at- 

 tention to the need for caution in drawing conclusions from experiments 

 on caterpillars in reference to the determination of sex. The morpho- 

 logical facts must be kept in view, and this fact in particular, that the 

 sex is often clearly marked at hatching, and is sometimes quite certainly 

 determined in the ovary. This was, he says, established years ago by 

 the investigations of La Valette St. George and of Brocadello. The 

 experiments of Mary Treat, Gentry, Landois, and Giard himself, in sub- 

 jecting caterpillars to restricted diet and so on, do not offer any general 

 physiological conclusion as to sex-determination. 



Experiments in Seasonal Dimorphism, f —- G. A. K. Marshall has 

 made in Mashonaland a number of experiments, especially with species 

 of Terias, in order to ascertain how far humidity alone, as apart from 

 heat, can be regarded as responsible for the marked differences between 

 the summer (wet) and the winter (dry) broods. 



From his results it seems probable that, in the case of those species 

 which are amenable to the influences of climate, the stimulus necessary 

 to induce seasonal change would consist in a combination of either 

 moisture and heat, or dryness and cold, and not in either of these factors 

 exclusively. 



Accessory Chromosome in Insect Spermatogenesis.^:— C. E. McClung 

 gives a brief abstract of a paper on this subject which he has written for 

 publication elsewhere. The structure called " accessory chromosome " 

 is identical with the " small chromosome " of Paulmier, and the 

 " chromatin nucleolus " of Montgomery. It is most distinct in the first 

 spermatocyte, has been recorded in a number of insects belonging to 

 different orders, and probably occurs elsewhere. The special peculiarities 

 are: — that it exhibits a remarkable uniformity of staining power, similar 

 to that exhibited by chromosomes in the metaphase ; that it occupies a 

 peripheral position during at least the spireme stage ; that it is isolated 

 from the chromatin reticulum and does not participate in its changes ; 



* Comptes Eendus, exxxiii. (1901) pp. 407-10. 

 t Ann. Nat. Hist., viii. (1901) pp. 898-403. 

 X Anat. Anzeig., xx. (1901) pp. 2'20-G. 



