630 EXPERIMENT STATION RECORD. [Vol. 36 



produced, 0.3075; number of stems on each plant with the qnantlty of seed 

 produced, 0.2771; numbei- of days to mature with quantity of seed produced, 

 0.19.54; number of leaves on each stalk with quantity of seed produced, 

 0.1217 ; days to mature with height of plant, 0.1748 ; percentage of sucrose in 

 the mother beet with days to mature seed, —0.1292 ; and percentage of sucrose 

 In the mother beet with number of leaves on each stalk, 0.2484. 



What is happening to the hawthorns? L. M. Standish (Jour. Heredity, 7 

 (1916), No. 6, pp. 266-279, figs. 11). — Summarizing the results obtained from a 

 study of Crataegus and from a review of contributions thereon, the author notes 

 the facts that among the members of this genus a remarkable amount of 

 comparatively recent multiplication of forms has become evident in the descrip- 

 tive literature and that the presence of large numbers of local species in a given 

 area is correlated with imusual sterility. Out of 171 specimens examined, only 

 35 could be regarded as being uncontaminated with regard to poUen conditions, 

 while 76 showed from 50 to 100 per cent abortive grains. A study of other 

 groups available Is said to show parallel conditions, the pollen being usually 

 good in the more widely distributed species but largely abortive in those of 

 restricted areas. 



The study of the genus Crataegus is said to give evidence of both systematic 

 and morphological character which is considered to indicate the widespread 

 occurrence of hybridism. The author concludes that among the members of 

 this genus, at least, extreme variability is linked with extensive hybridism and 

 the consequent multiplication of species rather than with mutation and the 

 problem of the saltatory origin of species. 



Influence of the composition and concentration of the nutrient solution 

 on plants grown in sand cultures, A. H. Ayres (Univ. Cal. Pubs. Agr. Sci., 

 1 (1911), No. 11, pp. S41-394, pis. 11, figs. 10). — The results are given of a series 

 of tests with a hybrid species of Nicotiana, the plants being grown in washed 

 sand and supplied with nutrient solutions containing sodium nitrate, calcium 

 phosphate, potassium sulphate, and magnesium sulphate. The salts were so 

 used as to give information regarding the separate compounds, the total con- 

 centration of salts, and the balance of salts in tlie solution, the height, leaf 

 length, leaf width, flower production, and dry weight of tops being taken as 

 indications of the influence of the solution on the growth of the plant. 



Nitrogen was found a more important growth-limiting factor than phos- 

 phorus, while phosphorus, in turn, was more important than potassium. Plants 

 grown in solutions of low concentration were in general superior to those 

 grown in solutions of higher concentration. The author claims that the 

 physiological balance of salts in the solution is an important factor which 

 must be taken Into consideration in connection with the composition and con- 

 centration of the solution, as growth is influenced by a combination of all these 

 factors. The concentration of the nutrient solution was found to affect the 

 economical use of nitrogen. Less calcium was absorbed from solutions at low 

 concentrations than from those that had a high total concentration, but It 

 seems to be used with greater economy in low concentrations than in high ones. 



A comparative study of nutritive solutions in sand and water cultures, 

 A. A. Stol'gane (Stolhane) (Iz RezuVt. Teget. Opytov Lab. Rabot (Rec. 

 Trav. Lab. Agron.), Moskov. Selsk. Khoz. Inst., 10 (19H), pp. 289-3S6).— 

 Experiments are reported in which a test was made of the comparative value 

 of nutritive solutions prepared according to the formulas of Hellriegel, Crone, 

 and Prianishnikov. From a study of barley and flax, the growth of plants and 

 the absorption of nitrogen, phosphoric acid, sulphur, potash, and calcium was 

 determined for the different solutions. Analyses arc given of different parts 

 of plants in the various cultures, from which it appears that the different 



