ZOOLOGY AND BOTANY, MICKOSCOPYj ETC. 557 



y. General.* 

 Growth by Intussusception-t — Prof. 0. Blitsclili discusses the 

 general question whetlaer we must suppose a growth of the plasma by 

 intussusception. He states the well-known theory, and notes its general 

 acceptance, and the recent criticism. Whatever be true of starch-grains 

 and cell-wall, in regard to the plasma itself intussusception has seemed 

 to most the only possible mode of growth. But the modern recognition 

 of the reticular, vacuolate, or webbed structure of protoplasm seems to 

 Biitschli to suggest another possibility. Like others, he distinguishes 

 in the Protozoon body two substances — the web-forming plasma proper, 

 the included more fluid chylema. The existence of such structures 

 makes it quite possible that newly formed plasma molecules are directly 

 apposed to the extremely fine walls of the plasmic web. 



Remarkable Case of Mutualism.:!: — Dr. C. P. Sluiter describes a 

 remarkable case of mutualism, in which two species of Trachicliihys (or 

 Amphiprion) live with certain large tropical Actiniae. The fishes swim 

 about between the numerous tentacles, notwithstanding the presence of 

 numerous stinging organs. Here the fishes appear to be safe against the 

 attacks of larger fishes, and they never go far from their hosts. While 

 there can be no difficulty in seeing the advantage to the fish, there is 

 but little in detecting the benefit to the Actinian. The continual move- 

 ments of the fish bring about an advantageous change of water ; and it 

 has been observed that one species brings food to the Actinian. 



B. INVERTEBRATA. 



Blood of Iiivertebrata.§ — M. L. Cuenot, after some remarks on the 

 general composition and function of blood, gives a brief account of the 

 results of his observations on various groups. Notwithstanding the 

 statements of Foettinger and Howell, he denies the existence of hasmo- 

 globin in Echinoderms; in them the amoebocytes are almost the only 

 nutrient parts of the blood. In Insects the liquid of the ccelom contains 

 a dissolved albuminoid, varying in colour, which has both respiratory 

 and nutrient functions. In the blood there are a number of typical 

 amoebocytes, which are produced by a large gland which completely 

 surrounds the heart, and even extends over the alaeform muscles ; this 

 gland is formed of a connective stroma filled with nuclei and fine granu- 

 lations. These nuclei gradually surround the albuminogenous ferment, 

 and escape from the gland. This lymphatic gland is found in the larv^ 

 as well as in the imagines of all orders of Insects, with the single excep- 

 tion of CJiironomus plumosus, in which there is hasmoglobin. In Scorpions 

 the lymphatic gland is an elongated body, situated on the dorsal part of 

 the nerve-chain ; it seems to be merely a spongy diverticulum of the 

 dorsal artery of the nerve-chain. 



In the crayfish, crab, and Pagurus the blood-fluid, in addition to its 

 ordinary albuminoids, contains amoebocytes with a yellowish ferment ; 

 these are produced by a gland which is situated in the gill, and which 

 is so arranged that the just oxygenated blood traverses it, and carries 



* This section is limited to papers which, while relating to Vertebrata, have a 

 direct or indirect bearing on Invertebrata also, 

 t Biol. Centralbl., vii. (1888) pp. 161-4. 

 X Zool. Auzeig., xi. (1888) pp. 240-3. 

 § Arch. Zool. Espe'r, et Ge'n., v. (1888) pp. xliii.-vii. 



