686 APPENDIX B. 



" This case is of additional interest, as it may serve to convince those 

 naturalists who are still inclined to maintain that acquired characters are 

 inherited, and to support the Lamarckian principle of development, that their 

 Tiew cannot be the right one. It has not proved tenable in a single instance " 

 (P- 54). 



Most readers of the foregoing pages will think that since Pro- 

 fessor Weismann has left one after another of my chief theses 

 without reply, this is rather a strong assertion ; and they will 

 still further raise their eyebrows on remembering that, as I have 

 shown, where he has given answers his answers are invalid. 



And now we come to the additions which I indicated at the 

 outset as having to be made certain evidences which have come 

 to light since this controversy commenced. 



When, by a remembered observation made in boyhood, joined 

 with the familiar fact that worker-larvae can be changed into the 

 larvae of queens by feeding, I was led to suggest that probably 

 all the variations of form in the social insects are consequent on 

 differences of nurture, I was unaware that observations and 

 experiments were being made which have justified this suggestion. 

 Professor Grassi has recently published accounts of the food- 

 habits of two European species of Termites, shewing that the 

 various forms are due to feeding. He is known to be a most 

 careful observer, and some of the most curious of his facts are 

 confirmed by the collection of white ants exhibited by Dr. David 

 Sharp, F.R.S., at the soiree of the Royal Society in May last. 

 He has favoured me with the following account of Grassi's results, 

 which I publish with his assent : 



" There is great variety as to the constituents of the community and 

 economy of the species in White Ants. One of the simplest conditions known 

 is that studied by Grassi in the case of the European species Calotermes flavi- 

 collis. In this species there is no worker caste ; the adult forms are only of 

 two kinds, viz., soldiers, and the males and females ; the sexes are externally 

 almost indistinguishable, and there are males and females of soldiers as well 

 as of the winged forms, though the sexual organs do not undergo their full 

 development in any soldier whether male or female. 



" The soldier is not however a mere instance of simple arrested develop- 

 ment. It is true that there is in it arrested development of the sexual organs, 

 but this is accompanied by change of form of other parts changes so extreme 

 that one would hardly suppose the soldier to have any connection with either 

 the young or the adult of the winged forms. 



" Now according to Grassi the whole of the individuals when born are 

 undifferentiated forms (except as to sex), and each one is capable of going on 

 the natural course of development and thus becoming a winged insect, or can 

 be deviated from this course and made into a soldier ; this is accomplished by 

 the White Ants by special courses of feeding. 



" The evidence given by Grassi is not conclusive as to the young being all 

 born alike ; and it may be that there are some individuals born that could 

 not be deviated from the natural course and made into soldiers. But there 

 is one case which seems to show positively that the deviation Grassi believes 



