RECENT WORK OX MOSSES AND FERNS. 375 



chief object appears to be the production of as many matured 

 spores as possible. Other things being equal there would 

 thus be an a priori improbability confronting any suggestion 

 of reduction ; and on this account we should deprecate any 

 free resort to this as an explanation of morphological 

 difficulties in homosporous forms. It is more reasonable to 

 suggest that it has occurred in heterosporous forms, for in 

 these the tendency is not to mere numerical spore-produc- 

 tion, but towards the perfection of a smaller number 

 suitably equipped with nutritious stores, so as to tide over 

 the organism more securely to the time when the embryo 

 can manage for itself. We need not necessarily assert that 

 reduction has never taken place in homosporous Pterido- 

 phytes ; other circumstances may have conduced to it. But 

 the dominant feature has no doubt been the production of 

 as many spores as possible, and considering this circumstance 

 we should look critically at any suggestion of reduction in 

 homosporous plants, and only accept it as probable when 

 some good physiological reason can be assigned for its 

 having occurred. 



From the above pages it will be seen that opinion on 

 the Archegoniatae is now in a state of flux. Little is 

 definitely known, and the facts are often susceptible of 

 various interpretation. To those who lay greater stress on 

 one character a certain conclusion may seem clear ; by those 

 who select another character as more important, the con- 

 verse conclusion may be arrived at, and be held with equal 

 tenacity. The whole would seem to turn upon the selec- 

 tion of the characters to which weight is to be attached. 

 Whatever may be the shortcomings of recent work, and 

 recent argument, one point seems to emerge with clear- 

 ness. Relationships, especially among ancient forms, are not 

 to be based upon comparison of characters which are directly 

 variable in a high degree in the individual under changing 

 conditions of present life. It has been conclusively shown 

 that the vegetative characters of the gametophyte are often 

 so influenced in Mosses and Ferns, and we accordingly 

 conclude with some degree of certainty that relationships 

 based on that foundation are insecure, and especially so 



