206 SUMMARY OF CURRENT RESEARCHES RELATING TO 



average width of the pith-rays is 14 cells, or 0*29 mm., with an average 

 height of 1 ' 36 mm., or 60 cells. In P. Wrightii the average width is 

 8 cells, or 0"16 mm., with average height of 84 cells, or 1 "84 mm. In 

 P. racemosa the average width is 5 cells, or ■ 9 mm., with an average 

 height of 107 cells, or 2 "36 mm. 



Resin Secretion in Balsamorrhiza.'^ — E. C, Faust has studied the 

 secretion of resin in Balsamorrhiza sagittata in order to discover the 

 origin of the secretory tissues and the cause of the secretion. This 

 species is the most prominent plant of the inter-mountain of Wyoming 

 (British Columbia), and depends upon the growth of the root-stock for 

 propagation ; flowers are produced in the third or fourth season. The 

 radicle is of the tetarch type. The resin-canals arise in two concentric 

 rows above and within the root-stock, with radial canals between the 

 longitudinal ones of the primary series. In the lowest parts of the root- 

 stock and in the subsidiary roots only the outer series of canals is found. 

 There is also a double series of canals in the stem and leaves, viz. an 

 outer series in cavities of the cortex opposite the interfascicular regions, 

 and a second inner series. The root-canals and the stem-canals have a 

 separate origin, and remain distinct. The canals do not appear until 

 resin has been formed in the meristem. Balsamoresene and balsamo- 

 resinic acid are formed from inulin in this species, probably by 

 polymerization and reduction. The resene and the resinic acid derived 

 from it are both toxic in character. Secretion is dependent on physio- 

 logical activity in the meristem, inulin being used in anabolism, and the 

 resine and the resinic acid being waste products. The two latter 

 substances are transferred to schizogenously-formed secretory-canals. It 

 thus appears that " a polysaccharide, inulin, produced during photosyn- 

 thesis, is broken down, thus causing a bye-product, balsamoresene, to be 

 produced. This resene is then changed to resinic acid." 



Reproductive. 



Development of Pollen in Salvia-f— P. Guerin contributes a short 

 note upon the stamen and the development of the pollen in Salvia. As 

 the result of studying the different stages of growth in numerous species, 

 the writer concludes that the development of the pollen varies with the 

 species. Sometimes the pollen mother-cells form one layer and at other 

 times two layers. The inferior branch of the connective may or may 

 not be fertile ; in S. splendens it is rarely so ; in S. canariensis it is 

 frequently so ; while in a number of other species it is the normal condi- 

 tion. The loculus is always smaller than that of the upper branch and 

 may be reduced to a single pollen-sac, as in *S'. canariensis, in S. officinalis, 

 S. interriipta, 8. triloba, 8. plebeia, etc., there are two sacs. A number 

 of species, including 8. officinalis, must therefore be regarded as having 

 bilocular anthers with loculi of unequal size. 



* Bot. Gaz., Ixiv. (1917) pp. 441-79 (4 pis. and 2 figs.), 

 t Comptfes Eendus, clxv. (1917) pp. 1009-12. 



