126 SYDNEY H, VINES. 



of experiments which leave no doubt as to the incorrectness 

 of PfefFer's theory. When the filamentous cells of Vaucheria 

 were cut across, a rounded mass, consisting of endoplasm 

 and cell-sap was, discharged, and he could distinctly see the 

 free borders of the remaining ectoplasm inclining towards 

 each other and finally coalescing, and thus closing up the 

 wound. Many observers^ regard the ectoplasm as being 

 merely the hyaline substance which is the basis of the 

 protoplasm, but Prof. Strasburger believes that his observa- 

 tions indicate that it is a definite modification of this ground- 

 substance ; which is endowed with various properties quite 

 distinct from those of the ground-substance or basis of the 

 endoplasm. He must not, however, be understood to mean 

 that a surface-layer (" Oberflachenhautchen," " Contact- 

 membran," Max Schultze) is not formed upon the surface of 

 masses of naked protoplasm when exposed to the action of . 

 air or of liquids. He only objects to the identification of 

 such a layer, formed in a purely mechanical manner with the 

 ectoplasm, which he regards as the product of a true process 

 of diiferentiation. 



From the foregoing observations w^e may infer that the 

 simplest form in which protoplasm occurs is that of a uni- 

 formly granular mass, and that the first step toward a 

 greater complexity of structure is the differentiation of an 

 external hyaline layer which invests the more fluid internal 

 granular portion. We will now follow Professor Strasburger 

 in his researches into the intimate structure of these two 

 substances. 



1. The ectoplasm. 



In his account of the plasmodia of Myxomycetes, to which 

 allusion has already been made, Hofmeister" calls attention 

 to the fact that the ectoplasm presents a radial striation, and 

 occasionally a striation running parallel to the free margin. 

 Sachs' finds a similar aj^pearance in the ectoplasm of 

 the zoogonidia of Vaucheria; Tschistiakoff ^ finds it also 

 in the " primordial utricle " of the pollen grains of Conifers, 

 and Strasburger alsofound it in the ectoplasm of rapidly grow- 

 ing cells when he was investigating the process of division in 

 Spirogyra orthospira. In order to arrive at the true signifi- 

 cance of these appearances, he made a series of experiments 

 with a variety of reagents upon the zoogonidia of Vaucheria 



» Sachs : ' Lchrbucb/ 4th ed., p. 41, 1874. 



- ' Pflanzenzellc,' p. 24. 



' ' Lehrbuch,' p. 41. 



■• 'Bot. Zeitung,' 1875, p. 99. 



