706 TRANSACTIONS OF SECTION K. 



suggests that there is only one matrix from which all qualities arise, and that 

 (without introducing any fresh stuff of existence) the secondary qualities, life, 

 and, at a still higher level, mind, emerge by some grouping of the elements within 

 the matrix. The development of this idea as it applies to life would appear to 

 offer a real point of contact between inductive biological work- and philosophy. 



To return to our plant, its development, with increase in size and progressive 

 complexity of external form and internal structure, must be considered. The 

 power of continued development possessed by most plants and wanting in most 

 animals makes comparison between the two kingdoms difficult. That there is no 

 fundamental difference between the continued and the definitely limited types 

 of embryogeny is, however, shown by plants themselves. The bryophyte 

 sporogomum is a clear example of the latter, while the fern sporophyte is one of 

 many examples of the former. A difi'erenC'e less commonly emi^hasised is that in 

 the sporogoniura (as in the higher animals) the later stages of development 

 proceed by transformation of the whole of the embryo into the mature or adult 

 condition ; in the fern-plant the apical development results in successive addi- 

 tions of regions which then attain their mature structure by transformation of 

 the meristematic tissue. 



These distinctions are of some importance in considering the generalisation 

 originally founded on animal development and known as the biogenetic law. 

 That ' the ontogeny is a concise and compressed recapitulation of the phylogeny ' 

 is essentially a phyletic conception. It has been more or less criticised and chal- 

 lenged by some distinguished zoologists, and has always been difficult to apply to 

 plants. If we avoid being prejudiced by zoological theory and results, we do not 

 find that the characters of the embryos of plants have given the key to doubtful 

 questions of phylogeny. What help do they give us, for instance, in the Algie 

 or the Vascular Cryptogams '! The extension of the idea of recapitulation to the 

 successively formed regions of the seedling plant requires critical examination ; 

 if admitted, it is at any rate something different from wiiat the zoologist usually 

 means by this. The facts — as shown, for instance, in a young fern-plant — ^are 

 most interesting, but can perhaps be better looked at in another way. Develop- 

 ment is accompanied by an increase in size of the successively formed leaves 

 and portions of stem, and the process is often cumulative, going on more and 

 more rapidly as the means increase until the adult proportions are attained. 

 The same specific sj'stem of relations may thus find different expression in the 

 developing plant as constructive materials accumulate. I do not want to imply 

 that the question is merely a quantitative one ; quality of material may be involved, 

 or the explanation may lie still deeper. The point is that the progression is not 

 a necessary one due to some recapitulative memory. 



There are some other classes of facts, clearly cognate to normal individual 

 development, that seem to require the causal explanation. I may mention 

 three : (1) Vegetatively produced plants (from bulbils, gemmae, &c.) tend in 

 their development to pass through stages in elaboration similar to young plants 

 developing from a spore or zygote. The similarities are more striking the 

 smaller the portion of material from which a start is made. (2) Branches may 

 repeat the stages in ontogeny more or less completely also in relation to differ- 

 ences in the nutritive conditions. (3) In the course of continued development 

 there may be a return to the simpler form and structure passed through on the 

 way to the more complex. These cases of parallels to, or reversals of, the 

 normal ontogenetic sequence suggest explanation on causal lines but are diffi- 

 culties in the way of phyletic recapitulation ; the first two cases can be included 

 under this, while the third seems definitely antagonistic. On the whole it may 

 be said that recapitulation cannot be accepted for plants without further 

 evidence, and that preliminary inquiry disposes us to seek a deeper and more 

 fruitful method of explaining the facts of development. 



The aevelopment of most plant-individuals starts from a single cell, and 

 when we compare mature forms of various grades of complexity the unicellular 

 condition is also our usual starting point. What is not po generally recog- 

 nised or emphasised is the importance of the filament as the primitive 

 construction-form of most plants, I do not use the word ' primitive ' in a 

 phyletic sense, nor in the sense of an ideal form, but to indicate a real stage in 

 independent progressions underlying many homologies of organisation. I cannot 



