24 



A FLOKA WITHIN ANIMALS. II. 



after, however, the movement is reversed, the globules successively burst, and be- 

 come at first faintl.y purplish, and afterwards brownish. The protoplasma and 

 granules are colored a deep or intensely reddish brown. 



With nitric acid, and the subsequent addition of aqua ammonia, the cell-contents 

 become a confused mass of a beautiful amljer color. 



Solution of iodine, acetic acid, solution of chloride of sodium, aqua ammonia, or 

 the lon"-coutinued action of water, give rise to a destruction of the different parts 

 of the cell-contents, and causes a general shrinking of the mass from the inner sur- 

 face of the cell-wall, the whole apparently held together by the continuity of the 

 primordial utricle, which now presents a shrivelled, faintly granular appear- 

 ance (IV. 2). 



Occasionally, dead individuals of Enterobryus are met with in which the cell- 

 contents are observed to have shrunk to two-thirds or even one-third their original 

 extent, presenting a shrivelled, irregular, granulo-membranous appearance (PI. IV. 

 1). The ordinary structural elements of the mass have disappeared, and in their 

 place yellowish, globular, oil-like bodies are found of various sizes, from a granule 

 up to one-fourth the diameter of the cell, occupying a position within, and exterior 

 to, the shrivelled primordial utricular mass (1, c). 



No circulatory movement of the character of c^'closis is ever observed in the cell- 

 contents, nor can any molecular movement be perceived. Upon the rupture of a 

 cell, however, and the escape of its contents, the finer granules exhibit slight 

 movements of the kind just mentioned (PI. I. 1,/). 



2. Of the Secondary Cells. — (PL 1. 1, e; 4, d.) In the fully developed Eiiterohryus 

 there are usually two secondary cells ; but occasionally there is only one, and very 

 rarely there are even three. 



In Enterobryus attenuatus, I have never been able to detect tw^o secondary cells, 

 and only in a few instances have I seen one ; arising probably from the more rapid 

 separation of these cells, after their development, in this species than in the others 

 (PL III. 15, 16). A rapid separation of the secondary cells would also account for 

 the truncated appearance of the distal extremity of the principal cell, and the great 

 thinness of the .cell-wall forming the truncated face, which is often observed in 

 Enterobryus attenuatus, and but rarely relatively in the other two species (17). 



Ordmarily, where two secondary cells exist, as in Enterobryus elegans and Ente- 

 robryus spiralis, they are oblong tubnlar, and the penultimate cell is usually a little 

 longer, narrower, and more cylindrical than the terminal cell. 



The latter is more or less cylindro-clavate, obtusely rounded at the distal end, 

 and curved. 



The contents of the secondary cells are of the same character as those of the 

 principal cell. They generally contain a very much greater proportion of the 

 granular matter than the principal cell, and freciuently may be observed to be 

 filled with granules to the exclusion of globules, the reverse of which I have never 

 seen (PL I. 1). 



When a third secondary cell exists, which I have observed in two or three 

 instances among some thousands of filaments of Enterobryus elegans, two are alike, 



