ITS CHEMICO-PHYSICAL AND MORPHOLOGICAL PROPERTIES 



20 



Towards its edge the plasmodium becomes broken up into a 

 number of threads of protoplasm, which are sometimes exceedingly 

 thin, and sometimes somewhat thicker, and which unite together 

 to form a fine network. In the thicker threads it is possible to 

 distinguish both a thin layer of homogeneous ectoplasm, and 

 also the endoplasm which it encloses ; these cannot, however, be 

 made out in the thinner ones. Throughout the whole mass of 

 protoplasm, which is sometimes very extensive, a large number 

 of minute nuclei are seen to be distributed. 



Amongst the Reticularia, of which many different kinds occur 

 in fresh and salt water, Gromia oviformis (Fig. 10) is especially 

 well known, in consequence of the experiments which have been 

 made upon it by Max Schultze (I. 29). 

 Part of the granular protoplasm, which 

 contains a few small nuclei, lies within 

 the oval shell, in which there is a wide 

 opening at one pole, whilst the re- 

 mainder protrudes through this open- 

 ing, covering the surface of the shell 

 with a thin layer. If the organism 

 has not been disturbed, very delicate 

 threads of protoplasm (pseudopodia) 

 stretch out from this layer into the 

 water in every direction ; sometimes 

 these psendopodia are exceedingly 

 longi many become forked, others 

 break up into numerous minute 

 threads, whilst yet others send off side 

 branches, which unite with neighbour- 

 ing pseudopodia. 



FIG. 9. Chondrioderma difforme 

 (from Strasburger) : / part of a 

 fairly old plasmodium ; a dry 

 spore ; b the same, swollen up in 

 water ; c spore, the contents of 

 which are exuding ; d zoospore ; 

 e amoeboid forms, produced by 

 the transformation of zoospores 

 which are commencing to unite 

 together to form a plasmodium. 

 (In d and e the nuclei and con- 

 tractile vacuoles may be seen.) 



Dujardin gave the name of sarcode to the 

 peculiar substance of which the bodies of the 

 lower organisms, described above, are com- 

 posed, because, like the muscle-substance of 



the higher animals, it is capable of exhibiting movements. Influenced by 

 Schleiden and Schwann's cell theory, investigators attempted to prove that 

 sarcode was composed of a number of minute cells, so that the sarcode 

 organisms might be included in the cell hyp .thesis. However, the solution 

 to the difficulty was found to be in quite another direction. Investigators like 

 Cohn (I. 7) and Unger were the first to compare sarcode with the protoplasmic 

 contents of a plant-cell, in consequence of the similarity of the vital phenomena. 

 Finally, Max Schultze (I. 29), de Bary (I. 2), and Haeckel (1. 10) established 



