616 



SCIENCE 



[N. S. Vol. XLI. No. 1060 



normality a simple cystic condition of the 

 ovaries. Histologically and cytologically these 

 cystic ovaries differed from the normal cow's 

 ovary in but one essential respect, namely, 

 that they had no corpora lutea. 



The case described presents for consideration 

 certain definite and clear-cut results bearing 

 on the problem of secondary sex characters. 

 These are : 



1. This cow had been a perfectly normal 

 female and had performed all the reproductive 

 functions, both primary and secondary, of the 

 sex. 



2. It later assumed certain of the secondary 

 characters of the male, both in respect of 

 structure and behavior, with perfect definite- 

 ness, and, so far as the characters concerned 

 go, completeness. This change was, for ex- 

 ample, at least as complete and definite as any 

 of those described by Steinach- following cas- 

 tration and transplantation of gonads. 



3. The gonads of this animal, examined sub- 

 sequent to the change in secondary characters, 

 were exactly like those of a normal cow, save in 

 the one respect that the follicles were not 

 breaking and discharging ova, but were form- 

 ing follicular cysts or becoming atretic, and 

 because of this no corpora lutea were formed. 



(a) The interstitial secreting mechanism of 

 these ovaries was absolutely normal, both in 

 respect of number of cells, and the cytological 

 characteristics of the individual cells. 



(b) The germinal mechanism was perfectly 

 normal up to the point where ovulation should 

 occur. Then it failed to separate the ova from 

 the ovary. 



(c) The outstanding, and so far as we can 

 determine the only significant, anatomical and 

 physiological difference between the gonads of 

 this abnormal cow and those of a normal one, 

 consists in the fact that the former lacked 

 any lutear tissue. 



A detailed account of the case, with figures, 

 will be given in the complete paper. 



Eaymond Pearl, 

 Frai^k M. Surface 

 2 Steinach, E., ' ' Willkiirlicli Umwandlung von 

 Saugetiermannehen in Tiere mit ausgepragt weib- 

 liohen GeseMeehtscharaeteren und weiblicher 

 Psyche," Pfliiger's Arch., Bd. 144, pp. 71-108, 

 1912. 



a new theory regarding the feeding power of 

 plants'- 



The feeding power of plants has been a sub- 

 ject of a great deal of investigation during the 

 last half century. Undoubtedly mere casual 

 observation of the growth of wild and culti- 

 vated plants led investigators long ago to sur- 

 mise that there is a difference in the feeding 

 power of different species of plants. Numer- 

 ous carefully controlled experiments have re- 

 peatedly confirmed this idea. Of the impor- 

 tant mineral elements needed by plants, suffi- 

 cient phosphates in an available form are 

 most often lacking in a soil. It is largely on 

 this account that phosphates have generally 

 been used in testing the feeding power of 

 plants. Fortunately phosphates are also well 

 adapted to this study. With the rapidly in- 

 creasing use of phosphate fertilizers, the sub- 

 ject has become one of considerable economic 

 importance, since it may be possible that with 

 a proper selection and sequence of crops as 

 regards their feeding power, the cheap insol- 

 uble phosphate fertilizers may be used with 

 greater advantage. 



It was formerly supposed that insoluble 

 minerals were made soluble by plants through 

 the action of various acids secreted by the 

 plant roots. As is well known, later experi- 

 ments, especially those by Czapex, have dem- 

 onstrated that other than carbonic acid, plants 

 normally excrete at the most, only minute 

 traces of acids. There remains, however, no 

 question that practically aU plants excrete 

 through their roots large quantities of car- 

 bonic acid. Lately some investigators have 

 suggested that differences in feeding power 

 may be due to differences in amount of car- 

 bonic acid excreted by the roots. Experi- 

 mental data, however, lend little support to 

 this view, and hence indicate that there must 

 be something vastly more important in deter- 

 mining the feeding power of a plant. On re- 

 viewing the literature concerning the subject, 

 and considering the data obtained in this lab- 

 oratory, the writer was led to formulate the 

 following hypothesis: 



Plants containing a relatively high calcium 



1 Publication authorized by the director of the 

 Wisconsin Experiment Station. 



