ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 505 



Jones thought, due to differences in the time of year. Their blood is 

 remarkable for the large quantity of sea-salt which it contains, a drop 

 from a Maia laid on a glass slide and dried giving a large number of 

 crystals. Coagulation takes place very rapidly. Notwithstanding 

 the great variation in form of the leucocytes, it is possible to re- 

 cognize a common type ; a large number have the form of young 

 blood-corpuscles of oviparous vertebrates ; as they grow older they 

 present a number of granulations, and, as their nucleus is then often 

 small or altogether lost, the author is of opinion that the granular 

 condition represents the last stage in the development of these bodies. 

 The form and the size appear to differ considerably as we pass from 

 one species to another ; the form, which is always ovoid, appears to be 

 permanent so long as the blood is retained within the circulatory 

 cavities; as an example of this we may cite the case of Palcemon, 

 where the leucocytes found in the lateral lobes of the telson did not, 

 during a long period of examination, exhibit any amoeboid changes. 



Pyloric Ampullae of Podophthalmate Crustacea.* — F. Mocquard 

 describes the ampullae as forming the floor of the median part of the 

 pyloric duct ; in most cases they may be compared to two demi- 

 cylinders placed side by side, with the cavity upwards. The surfaces 

 are not, however, regularly cylindrical, for they are rounded and 

 truncated obliquely behind. Their inner edges unite to form a pro- 

 jecting longitudinal — interampullar — fold ; from their cavities and 

 from the sides of the fold there arise a large number of parallel 

 longitudinal crests, on the free edges of which there are rows of ex- 

 tremely fine setae ; from this arrangement there results a considerable 

 number of small prismatic canaliculi, directed from before backwards ; 

 the free edge of the posterior portion of each of these ampullar crests 

 is continued into a large seta, which is directed backwards and carries 

 extremely fine setae. A remarkable point in this arrangement is that 

 very slight differences are found even when the Stomapoda are com- 

 pared with the Decapoda. Similar ampullae are to be seen in the 

 larva? (and doubtless also in other forms) even when there is no 

 gastric armature ; while further, though absent in the Mysis, they 

 are to be found in the Mysis-stage. 



We never find any appreciable amount of food in the ampullar 

 cavities, and their functions would appear to be this: while the 

 nutritious matters which are difficult of digestion remain in the 

 superior portion of the pyloric duct, the more finely divided par- 

 ticles make their way between the interampullar fold and the side- 

 wall of the pylorus along a line parallel to, but in a contrary 

 direction to that of the setaa ; they are thus broken and brought 

 into a sufficiently fine state to enable them to penetrate into the 

 canaliculi, whence they pass backwards in a longitudinal direction. 

 In support of this view, the author directs attention to the fact that 

 the excretory ducts of the so-called liver empty their products not far 

 from the posterior orifice of the canaliculi, where the alimentary matters 

 and this secretion would therefore be brought into intimate contact. 



* Comptes Rendus, xciv. (1882) pp. 120S-11. 



