Presidential Address. F. T. Brooks. 19 



and in nuclear cycle, the differences are profound. Again, the 

 argument is often advanced that in certain groups of existing 

 algae, the phenomenon of parasitism exists, accompanied by 

 the partial or total loss of chlorophyll, as in Harveyella and 

 Chroolepus, and that this illustrates the way in which fungi 

 have arisen. Although these forms have wholly or partly lost 

 their chlorophyll they still reproduce in a purely algal manner 

 and show no approach to a fungoid nature. Now it is a general 

 beUef, and probably a correct one, that parasitism in the fungi 

 is a more recent development than saprophytism. Saprophytic 

 algae are exceedingly rare and show even less approach to 

 mycelial growth than do the parasitic forms. Saprophytism 

 and parasitism in the algae at the present day are exactly the 

 same phenomena as the occasional adoption of these modes of 

 nutrition in other holophytic groups, and have no significance 

 as regards the origin of the fungi, the peculiarities of which 

 must be sought elsewhere. If the fungi had been derived from 

 algae by the loss of chlorophyll, one would expect to find in 

 certain fungal forms at any rate, traces of the same type of 

 carbohydrate metabolism as that existing in the algae. Such 

 in point of fact does not occur, and an entirely different set 

 of carbohydrates is found in the fungi. 



The almost universal hyphal development of the fungi is 

 sometimes compared \\-ith the filamentous nature of many 

 algae. In most groups of algae, the filamentous tvpes pass over 

 into more complex forms in which longitudinal di\'isions of the 

 cells occur, and, in the higher forms of algae, tissues are present 

 closely similar in character to those of terrestrial green plants. 

 On the other hand, even in the most highly developed fungi, 

 longitudinal di\'isions of the cells are almost unknown, and the 

 tissue systems are of a type unique in the plant world. Here 

 again there is a great gulf fixed between the algae and the fungi. 

 If the two groups had been phylogenetically connected, the 

 higher fungi would probably have exhibited some of the types 

 of cell aggregation prevalent in the holophytic algae. The hyphal 

 development of the fungi can be looked upon as a pronounced 

 type of cell expression, potentially present in all li\ing cells, 

 which has been developed to an extreme degree in correlation 

 ^vith peculiar modes of nutrition. Whenever a somatic part of 

 an organism \\-ith an essentially absorbent function is embedded 

 in a nutritive medium, be that dead or alive, there is a tendency 

 to a hypha-hke type of gro\\'th, as, for example, in the rhizoids 

 and root hairs of green terrestrial plants. Again the growth of 

 a pollen tube in the tissues of the style is essentially hypha-like, 

 and the vegetative body of the Rafflesiaceae, a parasitic family 

 of flowering plants, is practically a mycelium. Even in animal 



