THE SARCODINA 237 



Hence the dimorphism of the adults is due to their parentage, and is not 

 necessarily related to the manner in which they reproduce. A microspheric 

 form is produced sexually, and is always an agamont ; a megalospheric form 

 is produced non-sexually, and may be either a gamont or an agamont. 



Very little is known of the life -cycle of the non-marine genera. The only 

 form of which the cycle is known with any approach to completeness is 

 Chlamydophrys stercorea, the only entozoic member of the order, which is 

 found in the faeces of various vertebrates ; a second species, C. schaudinni, is 

 distinguished by Schiissler (A.P.K., xxii., p. 366). The adult form has a 

 chitinous single-chambered shell, and its protoplasm contains a single nucleus 

 and a ring of chromidia. It reproduces itself vegetatively by binary fission, 

 and also by multiple fission producing gametes. In the gamete-formation, 

 according to Schaudinn (131), the nucleus is ejected from the shell together 

 with all foreign bodies, food-particles, etc. In the shell is left a small quantity 

 of protoplasm containing the chromidia, from which about eight secondary 

 nuclei are formed, and then the protoplasm concentrates round each nucleus 

 and divides up into as many cells, the gametes, each of which becomes a 

 biflagellate swarm-spore, and is set free. The gametes copulate and the zygote 

 encysts. In order to develop further, the cyst must be swallowed by a 

 suitable host and pass through its digestive tract. If this happens, the cyst 

 germinates in the hind-gut, setting free an amcebula which forms a shell and 

 becomes a young Chlamydophrys, living as a harmless inhabitant of the hind- 

 gut, and feeding on various organisms or waste products occurring there ; but 

 according to Schaudinn it may, under circumstances not yet defined or 

 explained, pass from the digestive tract into the peritoneal cavity, and 

 multiply there as an amoeboid form without a shell, thus giving rise to the 

 organism described by Leyden and Schaudinn, from ascites-fluid, under the 

 name Leydenia gemmipara. 



The Foraminifera as a group comprise a vast number of genera 

 and species, both recent and fossil, for an account of which the 

 reader must be referred, to the larger works. They are classified 

 by Lister (286) into ten orders (suborders ?), containing in all thirty- 

 two families ; Rhumbler (288) recognizes ten families in all. The 

 vast majority are marine, but some of the simpler forms, such as 

 Euglypha, are found in fresh water, and can scarcely be separated 

 from the Lobosa except by the characters of their pseudopodia, a 

 feature upon which great weight cannot be laid as an indication 

 of affinity. Until the life-histories of these simpler forms have been 

 studied, their true systematic position must be considered as some- 

 what uncertain. But the affinities of such genera as Euglypha 

 and Chlamydophrys would seem to be with the Lobosa Testacea 

 rather than with the Foraminifera. 



III. XENOPHYOPHORA. 



This group was founded by F. E. Schulze (290) for a number of 

 curious organisms of deep-sea habitat, the zoological position of 

 which was a matter of dispute. By Haeckel they were believed 

 to be sponges allied to Keratosa, such as Spongelliidce, horny sponges 

 which load the spongin-fibres of the skeleton with foreign bodies of 

 various kinds. Schulze established definitely their relationship to 



