59 



so far as one can see, develop just as readily and are just as easily- 

 separable from the plant as the joints themselves, whose main 

 function appears to be vegetative reproduction, and this develop- 

 ment of the fruit is itself a purely vegetative reproduction, for it 

 is from the areoles and not from the seed that the new plant 

 springs. Both forms also produce besides the ordinary short 

 cylindrical branches almost perfectly globular ones. These are 

 much more numerous upon the congested form. These globular 

 branches differ in no way from many of the green fruits of the 

 proliferous form, except that the fruits have borne flowers and 

 have the scar of it left at their apices. Neither contain seed but 

 there is invariably a rudiment of a seed-cavity in the fruits but 

 none of course in the branches. 



The chief thing to be noted here is that we have one form of 

 the plant with an open-branching habit producing some fertile 

 seed and coinparatively few vegetative branches ; and the other 

 having lost its seed-producing habit, has modified and increased 

 its facilities for vegetative reproduction at least ten -fold. In no 

 case have I been able to find seed in the proliferous form. Fruits 

 without fertile seed are common in the fertile form also and sel- 

 dom is there a full quota of fertile ones produced even here. 



To test still further the correlation between sterility and in- 

 crease in vegetative facilities of reproduction, an attempt was 

 made to discover whether the few proliferous fruits of the fertile 

 form were more likely to be sterile than the non-proliferous fruits 

 upon the same plants. An examination was made of a number 

 of proliferous and non-proliferous fruits upon two typical plants 

 of the fertile form with the following results. Of course, many 

 seeds were found with almost perfect shells but having aborted 

 embryos. Where there was any doubt, the seeds were cut open 

 and examined. Usually no dissection was necessary. Five pro- 

 liferous fruits from each plant were selected and both that at- 

 tached to the stem and the one growing from it were ex- 

 amined. 



The ten proximal fruits contained fertile seed as follows : 3, o, 

 O, o, 4, 4, I, o, 3, 2. The ten distal ones contained fertile seed 

 as follows : i, o, 10, o, o, o, o, 4, o, i. 



