THE MYCETOZOA 49 



high power (Fig. 7, b), but the appearance is so similar to that of 

 overlapping nuclei, that without the confirmation afforded by the 

 experiment above described, the conclusion, that in addition to a 

 periodic (?) increase by mitosis, the nuclei multiply by simpl< 

 division, could hardly have been accepted as secure. 



With regard to the distribution of the nuclei, it is to be observed 

 in stained preparations, in which the plasmodium has been suddenly 

 killed, that they appear to be as numerous in proportion to the bulk 

 of the protoplasm in the veins as they are in the film of the plas- 

 modium on either side of them. 



In size the nuclei vary from 2 '5 to 5 p. In the resting condi- 

 tion they present a well-marked reticulation and a distinct nucleolus. 



In mitosis a well-marked spindle is formed, and the chromosomes 

 are rounded and compact. In number the latter appear to be 

 about 8 or 9, in Trichia (see, however, p. 65). It may be noted 

 that as in other Protozoa the nuclear membrane is maintained 

 until after the separation of the chromosomes to form the daughter 

 nuclei. 



Contractile Facuoles abound in the peripheral layer of the plas- 

 modium, and may be readily seen in the expansions between the 

 channels. They are generally about 7-8 /A in diameter. 



The protoplasm contains abundant granules, of minute size, 

 the nature of which has not been ascertained. In one group of 

 Mycetozoa, the Calcarineae, granules of carbonate of lime abound 

 in the plasmodia. They are not present in other species, and their 

 relation to physiological processes is obscure. 



The plasmodia of many species are white, but those of others 

 are yellow, pink, purple, or green, and owe their colour to a fluid 

 pigment scattered in small drops through the protoplasm. In the 

 Calcarineae, the fluid pigment invests the granules of lime. 



The Food of Plasmodia. The plasmodia of the great majority of 

 the Mycetozoa feed on the decaying vegetable matter among which 

 they live. Their mode of nutrition must be regarded as both 

 saprophytic and holozoic, for they are able to absorb nutrient 

 matters in solution (cf. Stahl, 22) as well as to engulf their food. 

 Those living among leaves and under bark are found charged with 

 particles which have been ingested, and the undigested portions 

 are found strewn along the track they have traversed. Badhamia 

 utricularis is exceptional in feeding on living fungi (Stereum, Auri- 

 cularia, etc.), though it will also live and thrive on the same fungi 

 after they have become dried, if they are wetted again with water. 



Experiments have shown that proteids (coagulated albumen, 

 sclerotium cysts), taken in by plasmodia, are digested in vacuoles 

 into which an acid is secreted by the surrounding protoplasm (see 

 the experiments by Miss Greenwood and Miss Saunders, 10), 



