MICROSCOPIC FORMS OF ANIMAL LIFE. 



19 



FIG. 292. 



codio body of one of them had withdrawn itself for a considerable space 

 from the wall of the test, and that in the liquid which filled the inter- 

 val a number of Vibrio-like bodies (spermatozoids?) swarmed; while 

 numerous disk-shaped masses of protoplasm lay on the surface of the 

 body. After some time these showed lively amoeboid movements, creep- 

 ing about between the body of the parent and the wall of the test, and 

 ultimately escaping through its orifice. Each of them contained a nu- 

 cleus and contractile vesicle, and moved by means of blunt pseudopodia; 

 and it seems probable that they were embryoes which would in time 

 form the characteristic ArceUa-test. 



408. Many testaceous Amcebans have been recently discovered, which 

 form tests of remarkable regularity and sometimes of singular beauty; and 

 it is difficult to determine, in many cases, whether the minute plates of 

 which they are composed have been formed by exudation from their own 

 bodies, or have been picked up from the surface over which the animals 

 crawl. 1 There can be no doubt of this kind, however, in regard to the 

 Quadrula symmetrica represented in Fig. 292, whose sarcode-body is en- 

 cased in a pear-shaped test of glassy transparence, made up of a great 



number of square plates which 

 touch each other by their edges. 

 The sarcode body does not usually 

 fill the test; the intervening space 

 being occupied by a clear liquid, 

 and traversed by bands of proto- 

 plasm. In the posterior part of 

 the body is seen a large clear 

 spherical nucleus, with a distinct 

 dark nutleolus; and in front of this 

 are contractile vesicles, usually two 

 in number. 



409. Coccoliths and CoccospJieres. 

 This would seem the most appro- 

 priate place for the description of 

 certain peculiar little bodies found 

 very extensively diffused over the 

 deep-sea bottom, especially abound- 

 ing in the Globigerina-mud ( 480), 

 which may be considered as Chalk 

 in process of formation. It was in 

 the specimens of this mud brought 

 up by the ' Cyclops ' soundings in 

 1857, that Prof. Huxley first 

 found the Coccoliths (Fig. 293, 1, 

 2) which Dr. Wallich in 1860 

 found aggregated in the spherical 



masses which he designated as ' coccospheres ' (3 ). Regarding the gelatin- 

 ous matrix in which they were imbedded as a new type of the Monerozoa 

 described by Haeckel, having the condition of an indefinitely extended 

 plasmodiwri) Prof. Huxley proposed to designate it by the name Bathy- 

 bius, indicative of its habitat in the depths of the sea; and this idea was 



1 See especially the recent admirable work of Prof. Leidy on the Freshwater 

 Rhizopods of the United States (1880). It is to be regretted that its able Author's 

 time and opportunities did not permit him to follow-out the life-histories of the 

 many interesting forms which he has described and figured. 



Quadrula symmetrica, with extended pseudo- 

 podia. 



