164 Transactions. 



jnore clearly by ecological studies in New Zealand than the extreme plas- 

 ticity of many species and structures, and their rapid response to a change 

 of environment. This is so great in numerous instances that the idea 

 of ' normal ' loses its meaning." With regard to the lycopodiums the 

 experimental alteration of the environment will be a very difficult task to 

 attempt, owing to the fact that the spores undoubtedly need very particular 

 conditions for germination, and that the prothallus in many cases takes 

 many years to grow. Therefore such a paper as the present, which contains 

 no facts concerning the experimental cultivation of the prothalli and plants, 

 cannot decide whether or not the varieties of the species described are 

 actually true-breeding forms, although in some instances field observations 

 can indicate with some certainty whether or not a particular variety is to 

 be regarded as a hereditary polymorph. However, the details of field 

 observations and of the general biology of the species will be of use, it is 

 hoped, in indicating the degree of relationship of the species inter se, as also 

 of the difterent sections of the genus to which they belong. 



The five main characters in the Lycopodium plant which lend them- 

 selves well to a study of its variability are (1) habit of growth and external 

 form, (2) stem-anatomy, (3) nature of fertile region, (4) form and structure 

 oi prothallus, and (5) form of young plantlet. A natural classification of 

 the genus will necessarily have to take account of all these characters, and 

 must not be based upon any particular one. Professor F. 0. Bower's (4) 

 remarks on this subject may here be quoted : " The true basis for a natural 

 system of classification is not one or two characters arbitrarily selected, 

 but as many characters as possible. These characters will be found to 

 A^ary as we pass from type to type, and the question will arise as to the 

 relative ages of the extremes in these characters."' 



On the whole, the five main sections of the genus are each found to show 

 very consistently certain characteristic types of structure in each of the five 

 particulars just enumerated. This would seem to indicate not only that 

 these sections are natural ones, but also that the characters themselves 

 are closely interdependent. The stem-anatomy corresponds with the 

 habit of the plant, as also does the character of the fertile region ; and 

 the type of prothallus, along with the form of the sexual organs and of the 

 young plant, varies with the habitat. The genus as a whole being so widely 

 distributed, and the species possessing such noteworthy powers of being able 

 to spread themselves in new situations, it is not surprising to find that all 

 the main characters of the plant are in a highly plastic condition, and are by 

 no means so fixed in form as would be expected if the difterent sections of 

 the genus had been separate from a very ancient geological age. There 

 will thus be instances in which a species, while showing most of the typical 

 Ci-iafacterisuics Oi tlie section to wnicn ic oeiongs, possesses also in some 

 one character or other a well-marked peculiarity which will be interpreted 

 either as an extreme adaptation or as an instance of the retention of a 

 phylogenetic character. 



The New Zealand species afford many instances of interesting variations, 

 several individual species showing a remarkable range of variability in 

 the form of such important organs as the prothallus and the strobilus. 

 Besides the five main characters of the plant which are considered in this 

 paper there are others, such as the form of the sporophyll, the development 

 and form of the sporangium, the presence of a mucilage-canal in the leaf, 

 and the development of bulbils on the stem, which will doubtless be of 

 importance in indicating in conjunction with the main characters of the 



