202 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Milne-Edwards. He finds that the gland itself consists of a dorsal end- 

 sac and a ventral labyrinth, the two being connected by a single small 

 orifice only. The labyrinth leads into the duct by a number of con- 

 verging canaliculi, which open separately into it. The so-called vesicle 

 is a dorsal diverticulum of the duct without direct connection with the 

 gland. End-sac and labyrinth both take part in the formation of the 

 secretion, and are lined by cells of distinctly different types. In de- 

 velopment the end-sac is mesodermic, and originates in a syncytium 

 which becomes hollowed out, the constituents ultimately developing cell- 

 walls round this central vacuole. The duct and labyrinth are ectoHcrmic, 

 and appear before hatching. After hatching, the labyrinth obtains its 

 complex adult form by the development of numerous evaginations which 

 increase in size and form anastomoses. The vesicle arises late in larval 

 life as an evagination of the ectodermic sac, and the adult position of 

 parts is produced by differential growth. The author believes that the 

 antennal glands represent the nephridia of an Annelid, but is unable to 

 definitely homologise the different regions of gland and nephridium. 



Colour-Physiology of Hippolyte varians.* — Messrs. F.W.Keeble and 

 J. W. Gamble have investigated the nature, mechanism, and causes of the 

 colour changes of this prawn, well-known for its colour variability. The 

 colouring matter is contained in the chromatophores, which occur both 

 in the superficial tissues and also between the muscle-fibres, and as an 

 investment to gut, nerve-cord, liver, and other organs ; they may contain 

 red, yellow, and blue pigments. A very important observation is the 

 demonstration that the prawns pass through a daily colour-cycle. At 

 dusk they become a transparent blue or green colour, and at dawn 

 recover the tint of the previous day. The changes are periodic, and to 

 some extent independent of external agents, and expressive of a nervous 

 rhythm. Another important point is that, while the prawns are very 

 sensitive to alterations of light-intensity, they react very slowly to colour- 

 change in the surroundings not accompanied by marked differences in 

 intensity. Thus a dark prawn placed in a white porcelain dish became 

 transparent in a few minutes, but a green prawn placed on brown weed 

 preserved the green colour for a week or more. That is, sympathetic 

 colour-change is very slow, and appears to act only through change of 

 light-intensity, to which the animals are exceedingly sensitive. Colour- 

 changes due to light-intensity occur in detached limbs and in blinded 

 specimens. It would seem that in regard to mechanism : — (1) the periodic 

 change is due to intrinsic rhythmic nervous change ; (2) the eye is 

 important in modifying nervous control ; (3) local government plays a 

 part. The paper is published as yet in brief abstract only. 



Nauplius of Penseus.f — K. Kishiuouye records larvse of Peneeus of 

 all stages including the nauplius from Tokyo Bay and the Inland Sea ; 

 the nauplii have not been seen since the description of them by Fritz 

 Miiller in 1863. The youngest nauplius found was 1/4 mm. in length, 

 and its three pairs of appendages were unsegmented and short. In the 

 next stage they are elongated, divided into numerous minute segments, 

 and furnished with numerous bristles. Rudiments of four new pairs of 



* Proc. Koy. Soc, lxv. (1900) pp. 461-8. 



t Zool. An'zeig., xxiii. (1900) pp. 73-5 (3 figs.). 



