64 TRANS. ST. LOUIS ACACD. SCIENCE. 



for denying these lowly creatures a degree of consciousness of 

 what they are about, or even of what 'will result from their labors. 

 They have an object in view, and whether we attribute their per- 

 formances to reason or instinct depends altogether upon the mean- 

 ing we give to these words. Define instinct as "congenital habit,'' 

 or " inherited association," and most of the doings of the lower 

 animals may be very justly called instinctive. But I cannot help 

 thinking that the instinctive and reasoning faculties are both pres- 

 ent, in most animals, in varying proportion, the last being called 

 into play only by unusual and exceptional circumstances ; and that 

 the power which guides the $ Pronubjx in her actions differs only 

 in degree from that which directs a bird in building its nest, or 

 which governs many of the actions of rational man. 



I will conclude by referring to one practical phase of this sub- 

 ject. As the insect and its food-plant are inseparable under natural 

 conditions, the former doubtless occurs wherever the latter grows 

 wild. Pods of T. angustifolia which I gathered on the Black Hills 

 of Colorado, in 1867, all show the unmistakable holes of egress 

 of the larvae ; while those of T. rupicola from Texas, of T, 

 Whipplei from California, and of others from South Carolina 

 and Texas, now in the herbarium of Dr. Engelmann, all show this 

 infallible sign of having been infested. Through the courtesy of 

 the same gentleman, I have also received the moth, taken around 

 Yuccas, from South Carolina, and the pods of several species from 

 the same State and from Texas, while the larvae were yet working 

 in them. There is every reason to believe, however, that beyond 

 the native home of these plants the insect does not occur, except 

 where it has naturally spread or been artificially introduced ; and 

 it is an interesting fact that, so far as I am able to learn, the dehis- 

 cent species in the northern parts of this country and in Europe 

 never produce seed. 



The cocoons containing the dormant lar%ae can be very conve- 

 niently sent b}- mail from one part of the world to another, and b}"- 

 their aid our transatlantic florists may yet have the satisfaction of 

 getting seed from their Yuccas without any personal effort. 



