1 68 BOTANICAL GAZETTE [February 



species as occur on river banks, the stolons of which grow in the water, creeping 

 over the muddy bottom. Among these are Mentha aquatica, Lysimachia vulgaris, 

 Lycopus europaeus, Stachys palustris, partly also Potentilla reptans, Ranun- 

 culus repens, and Cynodon Dactylon. In these the vegetative reproduction is 

 amply secured by the ability of the fragments of the rhizomes and stolons to 

 root very easily, and at the same time the water currents help to disperse such 

 fragments over wide areas. The seedling stage of Butomus, various species of 

 Alisma, Sagittaria, Najas, and Potamogeton is described. The slow growth ot" 

 the primary root is characteristic, while the hypocotyl attains its final length 

 in a very short time, and before the root actually commences its increase in 

 length. The primary root stele in Butomus and in Alismaceae consists of a 

 single central vessel and of two strands of leptome diametrically opposite each 



other. In the Naiadarpqp nn tV»A nttmr VionH ^varoi -.raco^* r,~ a 



developed 



largest of which is usually located in or near the center, and there are also several 



ipond 



The 



hypocotyl exhibits a bilateral structure in Butomus and Alisma and no pericycle 

 was observed inside the endodermis. In the Najadaceae the bilateral structure 

 is much less pronounced, and no stomata were observed in the epidermis of the 

 hypocotyl of any of these plants. A very simple structure characterizes the 

 cotyledon; the chlorenchyma is homogeneous and contains only one vein near 



the ventral face. The seedling stages are very carefully described and figured 

 adding several interesting points to the knowledge of the structure of aquatic 

 plants.— Theo. Holm. 



Organic correlations.— East 1 * attempts a classification of correlations with 

 especial consideration of plant data. This is a little-known field at the present 

 time, but one of great promise for the future. The writer of course realizes that 

 this tentative classification awaits the accumulation of further data to place it on 

 any satisfactory basis. Correlations are considered as "somatic" and "gametic." 

 Under somatic correlations are classed: (i) correlated reactions to environment; 

 here are placed the experimental results of MacDougal in Raimannia and of 

 Tower in Leptinotarsa, although the indications are that these changes are 

 germinal and not somatic; (2) growth correlations between (a) non-homologous, 

 } b) n « raol °gous, and (c) meristic parts; (3) correlations in organs of a plant; (4) 

 interdependent and exclusive development; here is cited the case of Oenothera 

 lata, m which the broad-leaved character is associated with the "inability to pro- 



H " rP ^" UU ~ -"- for plants from 



j self -pollinated f 



constant 



•• East, Edward M., Organic correlations. Amer. Breeders' Assoc. 4=PP- ** 

 1908. 



and « , N ; ACD 1 ° UGAL > D - T -> Vail, A. M., and Skull, G. H., Mutations, variations, 



unouhrtT P 1 ° f ^ ° enothe ^- Carnegie Inst. Publ. 8i:pp. 9* *W ** 

 unpublished results of the reviewer. 



