Chap. IV.] from 1 838 to 185I. 



with some hastiness of decision, while it brought the really 

 important points everywhere into prominence and employed 

 individual facts to explain the general propositions, as should 

 always be done in a work intended for learners. But in 

 addition to this Unger's book contained much that was really 

 new and valuable, and among other things some very im- 

 portant remarks on the physiological characteristics of proto- 

 plasm ; and it pointed out for the first time the similarity 

 between vegetable protoplasm and the sarcode in Rhizopods, 

 which Max Schulze had before carefully described. In this 

 year Nageli also published investigations into the primordial 

 utricle and the formation of swarmspores in his ' Pflanzen- 

 physiologische Untersuchungen,' Heft I, which gave a new 

 insight into the physical and physiological characteristics of 

 protoplasm. It has been mentioned above that De Ban's 

 investigations into the Myxomycetes in 1859 had thrown 

 new light on the subject of protoplasm, and had called at 

 tention to vital phenomena connected with it, which, though 

 analogous to what had been before observed, were rendered 

 very striking from the circumstance that in this case the 

 protoplasm was not in microscopically small portions enclosed 

 by firm cell-walls, but moved about and showed changes 

 of shape in large, sometimes in very large, masses, that were 

 entirely free and unconfined. Here was the best opportunity 

 for making a nearer acquaintance with protoplasm and for 

 learning to recognise it as the immediate support of all 

 vegetable and animal life ; in succeeding years the zootomists 

 and physiologists Max Schulze, Briicke, Kiihne, and others 

 established the fact that the substance which lies at the 

 foundation of cell-formation in animals agrees in its most 

 important characteristics with the protoplasm of vegetable 

 cells. A more detailed account of modern researches on this 

 subject, which would moreover involve the examination of 

 Hofmeister's work of 1867, 'Die Lehre von der Pflanzen- 

 zelle,' does not fall within the limits of our history. 



