30 



THE AMERICAN MONTHLY 



[February, 



separately, we find a succession of in- 

 termediate forms in which the cells 

 are bound together by a more or less 

 firm mucous, or gelatinous substance, 

 some in layers of indefinite extent 

 and arrangement, others in well- 

 defined families. But however they 

 may be related, each cell, so 

 far at least as its merely vegetative 

 functions are concerned, is quits 

 independent of the others, for it pos- 

 sesses within itself all the powers ne- 

 cessary for its existence as a living 

 organism. In other words, these plants 

 belong to such a low stage of life, 

 that there is no distinction between 

 the cells, such as we find in higher 

 plants where certain cells contribute 

 to the formation of tissues, others 

 convey the nutrient sap, and still 

 others produce the organs of re- 

 production, the pistil and stamens. 

 It follows that in such low plants we 

 must look for all the phenomena of 

 growth and reproduction in each cell 

 — each cell is, in fact, a perfect plant. 

 Hence, no classification of these 

 plants based upon their manner of 

 growth, can be regarded as quite sat- 

 isfactory to the scientific student. 

 The tendency now is to base all clas- 

 sification upon the methods of repro- 

 duction, which, being the ultimate 

 process in the life of every organism, 

 characterize its mature stage and in- 

 dicate the point at which its develop- 

 ment was arrested in the course of its 

 evolution. 



Complication of structure results 

 from cell-division, but it is necessary 

 to observe that all cases of cell-divi- 

 sion do not lead to structural com- 

 plexity ; for in the case of strictly 

 unicellular protophytes or protozoa, 

 the production of new cells or gera- 

 mse, within the parent, leads to what 

 seems to be a multicellular stage. But 

 each new cell produced under such 

 circumstances is, physiologically and 

 anatomically, an independent indi- 

 vidual, in no wise dependent upon 

 the others for support, but capable of 

 separate existence. Hence, the multi- 

 cellular condition, when it thus oc- 



curs among the strictly unicellular 

 organisms, is in no wise a higher con- 

 dition of organization, but only a tem- 

 porary phase brought about for a 

 special end. It is only when the mul- 

 tiplication of cells is a phenomenon 

 of growth and the resulting cells 

 form constituent parts of the organ- 

 ism, that there is any advance in 

 structure. This is the case in an 

 ovum which, by repeated cell-divi- 

 sion, produces a morula. 



Carrying the ideas embodied in 

 this view one step further, it 

 should also be observed that 

 while the cell, in a physiological 

 sense, can be justly regarded as the 

 typical unit from which all living 

 forms are derived, as taught by the 

 generally accepted cell-doctrine, yet 

 the student of the lower forms of life 

 cannot fail to observe that all the 

 structures to be found in protophytes 

 or protozoa, as well as many 

 found in the higher planes of ex- 

 istence, do not result from cell-divi- 

 sion — that many of the appendages 

 such as carapaces, flagella, cilia pe- 

 duncles, etc., result from processes 

 of growth, or secretion, without cell- 

 division. 



The dictum that has so long been 

 taught by physiologists that all struc- 

 tures originate in cells, cannot longer 

 stand. 



The most complex cell is a ciliated 

 infusorian,and in these animals there 

 are many structures which must be 

 regarded as true secretions of the 

 cell, not produced by cell-division, 

 as usually taught. 



Sometimes on an old decaying log 

 by a brook along the road, or half 

 buried in forest soil where it is al- 

 ways moist, there will be found mass- 

 es of a soft, jelly-like substance. This, 

 when examined with a microscope, 

 may be seen to move. It is a mass of 

 living jelly. Is it an animal or a plant? 

 This question has puzzled the micro- 

 scopists for years, and even now they 

 are not all agreed as to the affinities 

 of the myxomycetes, as they are 

 called. Saville Kent, one of Eng- 



