196 LEMON. [VOL. I. 



b. Budding. - - Small strips of tissue from the margin of the 

 body or edge of a cut resemble buds in their capacity for growth 

 and differentiation. These false buds regenerate more rapidly 

 than larger portions of the body. To induce the growth of 

 buds an incision is made, partly severing a very narrow strip 

 (.5 mm.) of tissue, as shown by the lines in Figs. 6 and 10; 

 Fig. 6 a indicates the method by which the worms in Figs. 8 

 and 9 were produced, and Fig. 10 a indicates how Figs. 1 1 and 

 12 originated. 



In Fig. 7 the cut was made as indicated by the dotted line a. 

 The bud, which was 4 mm. long, regenerated a new head, with 

 brain, eyes, and cephalic lobes, in fourteen days. This head 

 was developed from tissue in the posterior third of the body. 

 Dalyell, 1 referred to by Randolph, thought that heads could 

 be developed from tissue of the anterior part of the worm only. 

 This idea is wholly disproved by Figs. 7, ir, and 12. At b, 

 Fig. 7, is seen a bud one day after being cut. 



i. Growth. - - The bud, not having sufficient muscular strength 

 to right itself against the larger part of the worm, heals with- 

 out uniting with it, as is the case so often with animals split 

 in the middle line. Growth begins very soon after the opera- 

 tion, being quite perceptible at the end of two days. It 

 occurs in two ways : first, by regenerating new tissue on the 

 cut edge of the bud ; and second, by the increase of length, 

 breadth, and thickness of the old tissue. 



ii. Differentiation of Nciv Organs. - - Along with the increase 

 in size the body becomes rounded off on the dorsal surface, and 

 the head becomes broader and thicker in the region of the brain 

 area when the cephalic lobes appear. Finally the eyes and 

 pharynx, where a pharynx is developed, appear almost simulta- 

 neously. 



In Fig. 8 the bud was formed by partly isolating a narrow 

 strip of tissue from the side of the anterior part of the animal, 

 as indicated by the shaded part a. About the time the cephalic 

 lobes appeared, which was twelve days after the operation, 

 the bud began to assert its independence, and was dragged 

 about by the stronger worm with its head extending in a pos- 



1 " Observations and Experiments on Regeneration in Tlanarians," p. 370. 



