DR. BEALE^ ON THE TISSUES. 259 



In all these cases the vessels grow with the other elements 

 of the tissue, and thus the conditions for unlimited increase 

 without order, in an irregular manner, and Avithout advantage 

 to the organism, are present, and may persist. These results 

 appear to depend more upon the circumstance that the restric- 

 tions under which the growth of the tissue occurs normally are 

 removed, than upon any special peculiarities of the morbid 

 growth itself. The conditions favorable to the development 

 of such structures are not the result of accident, but depend 

 upon changes which have occurred at an earlier period of 

 time, and these may, in the same manner, be referred back. 

 The hereditary nature of many of these growths, and the 

 symmetrical character of certain morbid processes, receive 

 something like an explanation from the view above given. 



Dr. Beale had endeavoured to indicate very briefly some 

 of the circumstances which probably determine the different 

 characters of various morbid growths, including those 

 tumours which have received the very inappropriate term of 

 benignant, and the numerous intervening forms which pass 

 by almost insensible gradations into those of a malignant 

 character. 



On vegetable tissues and starch. — A few specimens of 

 vegetable tissues were then examined in order to ascertain if 

 their structure and growth could be explained by the same 

 general doctrine which will account for the appearances ob- 

 served in the tissues of the higher animals, both in a state of 

 health as well as in disease. 



The characters of mildew, one of the simplest structures 

 in the vegetable kingdom, have been described, and a prepara- 

 tion of another fungus has been alluded to. In these, as in 

 the animal tissues, the germinal matter was coloured red with 

 carmine, and the formed material remained perfectly colour- 

 less. It is, however, desirable to examine the tissues of one 

 of the higher plants. 



A portion of the young leaf of the common mignonnette, 

 showing the germinal matter coloured red with carmine, and 

 a piece of the epidermis from the same plant, showing 

 numerous stomata, and in the youngest elementary parts 

 masses of germinal matter, stained with the carmine, were 

 then passed round. 



A small piece of the rootlet of the mignonnette was also 

 exhibited. The elementary parts in this specimen were very 

 beautifully coloured. A section of a common potato, near 

 the point at which a bud was being developed, was submitted 

 to examination. In many of the elementary parts, the pri- 

 mordial utricle, and the nucleus (germinal matter), are well 



