942 



SCIENCE. 



[N. S. Vol. V. No. 129. 



separately. For the first ten years the 

 changes were slight, but now they are 

 more and more marked with every genera- 

 tion, and in some of the lots the straight 

 and smooth roots are the most numerous." 

 Let us briefly trace the history of the 

 Chinese Primrose, which was introduced 

 into English gardens about 1820, but whose 

 natural habitat became known just seven 

 years ago. A variable plant in the wild 

 state, found growing on dry calcareous 

 rocks that are exposed to the broiling sun, 

 it might seem* to give little promise of re- 

 ward for horticultural skill. The first two 

 batches of seedlings reared greatly ex- 

 ceeded expectations, but for years these 

 were propagated chiefly by offshoots. Now 

 garden seeds are entirely used, and few 

 could identify the horticultural prize-taker 

 with the wild specimens collected for the 

 first time a few years ago by Dr. Henry 

 and the Abbe Delavay. 



As a somewhat different method of in- 

 quiry we have Schindler's comparisons of 

 wheat of the same variety grown in differ- 

 ent regions of the world. He finds that the 

 relative amounts of starch and protein vary 

 according to the locality, though samples 

 taken from any one region closely resemble 

 each other. 



(9) Graft plants. In the literature of 

 gardening the question has often been de- 

 bated whether the stock and graft recipro- 

 cally influence each other. Except in a 

 few rare cases, the negative position has 

 usually been taken, but the experiments of 

 Daniels*, if confirmed and extended, will 

 go far to demonstrate that deep-seated 

 modifications may take place which can be 

 transmitted by seed. "When he grafted the 

 cultivated turnip on the wild garlic mus- 

 tard (Sisymbrium Alliaria) the seeds of the 

 turnip produced plants that inclined more 

 to the wild stock. He next reversed the 



*Eev. Gen. de Botanique, 1894; Comptea Kendus, 

 1892. 



process by growing the wild plant on a cul- 

 tivated stock. He grew plants of the gar- 

 lic mustard; some of them he allowed to 

 grow on as control plants; others he grafted 

 on the cultivated cabbage. Seeds were 

 saved and sown from both lots. The for- 

 mer faithfully reproduced the features of 

 the wild parent. Plants reared from the 

 graft garlic seeds were not so tall, the leaves 

 were not so crowded and bore a distinct re- 

 semblance to the cabbage, they were of a 

 deeper green color, somewhat plaited, gave 

 a less marked odor of garlic and something 

 of the odor of cabbage. The roots were 

 less woody, the medullary parenchyma was 

 less thickened, the vascular cylinder was 

 reduced but the bast was increased, the 

 bark was more delicate, the chlorophyll 

 more abundant, and the intercellular spaces 

 were reduced as compared with the wild 

 parent. 



(10) Cecidial and domatial plants. "We now 

 approach a subject that is still involved in 

 considerable obscurity, but the bearing of 

 which we believe will greatly aid us in the 

 study of many cell phenomena. Plant 

 galls, or Cecidia, in the restricted applica- 

 tion of the term, include those outgrowths 

 on leaves or shoots that are caused by in- 

 sects or mites which undergo development 

 within masses of vegetable tissue, this tis- 

 sue being produced through excretion of a 

 chemical substance by the hatched grub. 

 Though varying greatly in size, form, con- 

 sistency and relative abundance, they agree 

 in that the type of tissue built up by the 

 infested plant is diagnostic of the particular 

 species of insect whose egg was deposited. 

 It is not at all uncommon to find eight to 

 ten different galls on one shrub or tree, 

 each rearing a distinct insect species with- 

 in. 



While these have long been known to 

 naturalists, it is only within the past 20 

 years that attention has been increasingly 

 turned to Domatia. These are plant- 



