FERTILIZATION AND CROSS-FERTILIZATION. 25 



wheat, there is a hne or partition formed through the protoplasm ; 

 cell multiplication takes place ; the whole enlarges and constitutes 

 a germ. The two kinds of protoplasm have contributed to the 

 formation of an entirely new individual, and we have a seed — an 

 embryo plant with a supply of food, the whole protected by integu- 

 ments. The lecturer remarked that the old analogies between plants 

 and animals in regard to fertilization can now be all thrown aside, 

 while between the fertilization of the higher and lower plants there 

 exist not only analogies but homologies, in an almost unbroken, 

 though not a straight line. 



After a recapitulation of the essential parts of the flower, and 

 the remark that the outer parts were not merel}' protective, but often 

 exercised the function of attracting insects, the lecturer proceeded 

 to the second part of his subject, viz., the means whereby cross- 

 fertilization is secured. This is one of the most fascinating parts of 

 vegetable ph3'siology. In the latter part of the last century a book 

 was written by Conrad Sprengel, on the intervention of insects in 

 fertilizing flowers. Sprengel read the puzzle rightly, concluding 

 that in the greater number of cases there is some provision, by 

 insect or other agency, to prevent self-fertilization ; but at that 

 time botanists were studying plants in their relations to each other, 

 and classifying them by means of dried specimens ; and his researches 

 in regard to living plants were overlooked. Early in the present 

 century the object of this provision was discovered by Thomas 

 Andrew Knight, the eminent English horticulturist and physiolo- 

 gist, to be the keeping down of all vagaries, and the prevention of 

 deviations from the parent type. Attention was called to this sub- 

 ject again in 1858 and 1862, by Charles Darwin, who was convinced 

 that occasional cross-fertihzation is the rule and not the exception. 

 In a work lately published in England, and soon to be reprinted in 

 this country, he gives the results of eleven years' practical research 

 in regard to close and cross-fertilization. By experiments with the 

 morning glory, and other fast growing plants, he found that self- 

 fertilization, even when eSectual, produces, in general, less vigorous 

 plants than cross-fertilization. 



The lecturer then demonstrated the means by which cross-fertili- 

 zation is secured. This portion of the lecture was illustrated by 

 diagrams ; first of the Aristolochia or Dutchman's pipe, in section, 

 showing the position of the anthers and stigma to be such that self- 

 fertihzation is impossible. In the common plantain the lower 

 4 



