CELLULAR TISSUE 231 



is the most complex and which are therefore placed at the other 

 extremity of the order, have their organs so deeply imbedded in cellular 

 tissue that this tissue always forms their investments and constitutes 

 for them a bond of communication. Hence the possibihty of those 

 sudden metastases, so well known to those who practice the art of 

 medicine. 



Compare the very simple organisation of the infusorians and polyps, 

 presenting nothing more than a gelatinous mass of cellular tissue, 

 with the highly complex organisation of the mammals, which still 

 presents a cellular tissue though enveloping a large number of different 

 organs ; you will then be in a position to judge whether the principles, 

 which I have drawn up on this important subject, are merely the 

 results of an imaginary system. 



Compare in the same way in plants the very simple organisation 

 of the algae and fimgi with the more complex organisation of a big 

 tree or any other dicotyledonous plant, and you will perceive that the 

 general plan of nature is everywhere the same, notwithstanding the 

 infinite variations of her individual operations. 



Take for instance the algae which grow under water, such as the 

 widely spread Fucus which constitutes a great family with different 

 genera, and such as the TJlva, Conferva, etc. ; their scarcely modified 

 ceUular tissue is conspicuous enough to prove that it alone forms the 

 whole substance of these plants. In several of these algae, the move- 

 ments of the internal fluids in this tissue have not yet given rise to 

 any signs of a special organ, and in the others they have only traced 

 out a few canals through which food is supphed to thoss reproductive 

 corpuscles, which botanists take for seeds because they often find 

 them invested in a capsular vesicle in the same way as the gemmae 

 of many known examples of Sertularia. 



We may then convince ourselves by observation that in the most 

 imperfect animals, such as the infusorians and polyps, and in the 

 least perfect plants, such as the algae and fungi, there sometimes 

 exists no trace of any vessels and sometimes only a few rudimentary 

 canals ; lastly, we may recognise that the very simple organisation of 

 these living bodies consists only of a cellular tissue, in which slowly 

 move the fluids which animate them ; and that these bodies being 

 destitute of special organs only develop, grow, and multiply or repro- 

 duce themselves by a faculty of growth and separation of reproduc- 

 tive parts ; for they possess this faculty in a very high degree. 



In plants indeed, even including those with the most perfect organisa- 

 tion, there are no vessels comparable to those of animals which have a 

 circulatory system. 



Thus the internal organisation of plants really consists only of a 



