April 3, 1896.] 



SCIENCE. 



499 



after attack and injury hy a certain insect 

 (not yet identified j. Normally the young 

 cactus sends up half a dozen or more mass- 

 ive stems, usually 5 to 10 feet high and 3 

 or 4 inches in diameter, beset with thorns 

 along each of the 5, 6, or 7 ribs ; subse- 

 quently branches spring from these stems, 

 and the plant gradually expands into a 

 clump or colony a dozen feet or yards across. 

 Thus far the plant remains an individual, 

 the product of a single seed ; and the period 

 of individual development undoubtedly 

 covers a long term of years, since the 

 younger branches remain vigorous long 

 after the original stems have died and de- 

 cayed. Now, so far as the observations go, 

 they indicate that the plant does not nec- 

 essarily or normally fructify during this 

 term of individual development, but that if 

 its insect enemy and mate chances to de- 

 posit eggs in the pulp toward the extremity 

 of branch or trunk several changes super- 

 vene. In the first place the eggs develop 

 and in due time the larvse emerge and feed 

 on the pulp ; then the branch shrivels, los- 

 ing a quarter or third of its diameter, and 

 a pilage of slender spines or stiff bristles 

 springs and soon covers the shrunken por- 

 tion, which may be a foot or more in length ; 

 next, under the protection of these spines, 

 a bright-colored flower is put forth, and this 

 in time is followed by the fruit. It is of 

 course to be borne in mind that this sequence 

 has not been studied as a succession of 

 stages in the same plant, but only as an un- 

 broken series of stages exhibited by many 

 plants, so that the sequence may not be re- 

 garded as established ; but, so far as the 

 observations go, they tend in that direction. 

 Essentially parallel to the behavior of the 

 cina is that of the dicotjdedonous bush 

 called by the Mexicans torotito (not yet 

 identified), the geographic distribution of 

 which is about the same as that of the cina. 

 For a long time this plant was a puzzle be- 

 cause no indication of the mode of repro- 



duction was perceived. It grows in a clump 

 of two or three or a dozen stems springing 

 from a single root, and the colony or clump 

 retains vitality much longer than individual 

 branches, which apparently spring up, at- 

 tain full growth, die, and decay, while yet 

 the colony survives, so that, as in the case 

 of the cina, the term of individual existence 

 is manifestly long. At length it was noted 

 that the extremities of the separate stems 

 or branches occasionally present an abnor- 

 mal appearance — tumescent, gnarled and 

 twisted, with leaves or petioles attached ; 

 and on dissection it was found that such 

 diseased twigs contain eggs or larvse. Then, 

 as the season progressed, it was found that 

 the tumescent twigs — and these only — some- 

 times bear small flowers and, quite rarely, 

 a nutty fruit. So in tliis case as in that of 

 the cina, the flowering appears to depend 

 on the development of an abnormal condi- 

 tion resulting from ovaposition by an insect 

 (which was not seen in the imago form ; 

 but it seems not to be a necessary stage in 

 in the history of any individual, since in 

 many cases the tumescent twig withers and 

 falls off without flowering and of course 

 without fruiting, while only a small propor- 

 tion of the flowers appear to produce nuts. 

 In this case, too, the observations are sug- 

 gestive, though not demonstrative, of an 

 ontogenic sequence ; yet it is to be observed 

 that the sequence is in precise accord with 

 the biotic relations prevailing in this dis- 

 trict, under which the tendency is to per- 

 petuate species by prolonging the life of the 

 individual rather than by multiplying prog- 

 eny, under which all living things tend 

 to enter a solidarity of remarkable perfec- 

 tion, and under which phylogenic develop- 

 ment is either forced and intensified or cut 

 off by the pressure of an adverse inorganic 

 environment. Granting the sequence, or 

 even admitting only the indubitable inter- 

 relations found in the region, it follows that 

 the living things of the desert conserve 



