DR. BEALE^ ON THE TISSUES. 243 



was observed tliat in tlie rapidly growing parts of the plant 

 the layer was exceedingly thin — so thin that its existence 

 could hardly be demonstrated ; while in other specimens the 

 thickness of the formed material was very great indeed. In 

 the first instance the germinal matter was rapidly extending 

 itself. In the last^ in consequence^ probably^ of the existence 

 of conditions adverse to the free growth of the plant, the 

 germinal matter had sloAvly undergone conversion into formed 

 material — a certain amount of nutrient matter was absorbed, 

 so that the whole mass had increased in size — but had the 

 conditions been favorable, many times the quantity of formed 

 material would have been produced in the same period of 

 time ; but this would have extended over a very much larger 

 surface, and, of course, a greater proportion of germinal 

 matter would at the same time have been formed. 



Theories generally held. — Cell theory; Wolff's theory, as 

 modified by Professor Huxley ; Virchow's vieiv ; Dr. Bennett's 

 view. — Dr. Beale had endeavoured to show that in some in- 

 stances a cell- wall exists, and that in many there is no cell- 

 wall at all, while in others it is impossible to distinguish 

 between the cell-wall and the so-called cell-contents. The 

 idea of Schleiden, accepted by Schwann, that the nucleus 

 was precipitated from a fluid like a crystal, and the cell-wall 

 afterwards deposited around it, has been often contradicted 

 by actual observation, and it is difficult to see what object 

 could be fulfilled by such a process. 



A modification of Wolfl"^s view has lately been strongly 

 advocated by Professor Huxley, and has been made by him to 

 harmonise with the notions entertained with regard to the 

 nature of the intercellular substance. It is supposed that 

 originally a clear, homogeneous plasma is produced, in which 

 spaces (vacuoles) are formed, and these contain, in the 

 interior, the endoplast, consisting, in fact, of the primordial 

 utricle of the vegetable cell, the cell- contents, and the 

 nucleus. 



The walls of these spaces are composed of the original 

 plasma altered, which is termed the periplast, or periplastic 

 substance. The greatest importance is attached to the peri- 

 plast. It is supposed to possess the active power of growing 

 in and forming partitions, when division of the endoplasts 

 occur, and of becoming diff'erentiated into very important 

 structures. The intercellular (periplastic) substance is con- 

 sidered thoughout Germany as a most important structure, 

 and it is generally believed that its peculiarities are not 

 dependent upon the cells it contains, but are due to powers 

 residing in it. Mr. Huxley's views may be gathered from 



