186 SUMMARY OF CURRENT RESEARCHES RELATING TO 



almost invisible; the nucleoli resist the action for a longer time. 

 Acetic or chromic acids (1 per cent.) or concentrated picric acid bring 

 out the details of the nucleus, the disks of the cord, the rings at the 

 extremities, and the nucleoli. After giving an account of the action 

 of various colouring matters, the author says that he thinks no one 

 will doubt that the cord is homologous with the intranuclear network 

 of other nuclei ; and that it is not, as most have supposed, really 

 formed of homogeneous filaments, continuous with the nuclear mem- 

 brane, and largely ramifying and anastomosing. The network has 

 nearly always been described after the action of reagents on it ; it is 

 now seen how much these affect its original characters. 



The nuclei of the cells of the larvfe of Chironomus may be looked 

 upon as very complex elements, offering a true organization, if by that 

 term we understand an assemblage of parts having fixed and constant 

 relations to one another, and fulfilling special functions. As to the 

 functions of this apparatus and its mode of activity, hypotheses are at 

 present useless ; not only animal, but also vegetable cells must be 

 more closely studied, and the two carefully compared. In conclusion, 

 notice is taken of the observations of Baranetzky on the pollen-cells 

 of Tradescantia, where obscure transverse striee were seen in the 

 nuclear filaments, and a clear intranuclear substance, comparable to 

 that found in Chironomus, was detected. 



7. Arachnida. 



Structure of the Dermaleichidse.* — After describing in detail 

 the mouth-parts of these Arachnida, Dr. G. Haller directs attention 

 to certain characters in the digestive tract which point to their close 

 affinity with the Tyroglyphida and Dermacara; the tract being 

 simple, and the saccular stomach divided into two parts, lying one 

 behind the other, and not differing in function. 



So again, in the structure of the male organs we find a not incon- 

 siderable resemblance to the Tyroglyphida ; the testes and their ducts 

 are paired, the seminal vesicle and reproductive organ are unpaired, 

 while the male is provided with organs of attachment, and with 

 accessory organs developed on the extremities. Further investigation 

 into details proves, however, that we have here to do with forms of a 

 more lowly organization. Two, and in some cases three, different 

 forms of females were observed. The first of them was impregnated 

 by the male, but had no indications of any generative organs ; the 

 next had a matured ovum in its oviduct. The former of these is really 

 an eight-legged larval form, and it is only in the next stage that the 

 matured female is really present. The author justly directs attention 

 to this remarkable peculiarity. 



5. Crustacea. 



New and rare French Crustacea.f — M. Hesse here describes 

 Bimonaste bicolor and Scotophilus tricolor, two parasitic Copepods 



* Zeitschr. f. wias. Zool., xxxvi. (1881) pp. 367-88 (2 pis.)- 

 t Ann. Sei. Nat. (Zool.) xi. (1881) art. No. 8, 19 pp. (2 pis.). 



