348 Mr Willis, On Qynodioecism in the Labiatae. [May 30, 



On the above extreme hypothesis that the ocean consists of 

 condensed steam emitted from the interior, the solid ejectamenta 

 of volcanic action would have had a very subsidiary effect in re- 

 ducing the internal temperature. 



There remains the consideration of the heat converted into the 

 work which has been expended in producing elevations of the 

 surface, in shearing and contorting the materials of the crust, and 

 in inducing molecular changes. The amount of this work has no 

 doubt been from first to last enormous ; but it is easy to see that a 

 very inconsiderable fall of temperature throughout the interior 

 would represent a very great deal of such work effected. For 

 instance, the work of raising through half its height a layer of 

 granite ten miles thick, weighing 178 pounds per cubic foot, would 

 represent the heat equivalent to a fall of temperature of only 

 one degree F. throughout the globe. 



We have not then so far arrived at an answer to the enquiry — 

 What has become of all the heat generated by tidal friction ? 

 There appear to be only two replies to this question. One is, that 

 the solidification of the crust took place a very long while subse- 

 quent to the genesis of the moon, so that the still liquid surface 

 was able for ages to radiate directly into space the heat carried 

 up to it from below by convection during the time, when, owing to 

 the proximity of the moon, the generation of internal heat went on 

 most rapidly. The other answer can only be, that the moon was 

 not originally thrown off from the earth, but was left behind accord- 

 ing to the nebular hypothesis. In that case the whole amount of 

 tidal action would not have been so great, though nevertheless 

 sufficient heat may have been centrically generated by it to main- 

 tain those internal currents, which the theory of a thin crust and 

 liquid interior appear to necessitate. 



(2) On Gynodicecism in the Labiatae. (First paper.) By 

 J. 0. Willis, B. A., " Frank Smart " Student in Botany, Caius 

 College. 



In July, 1890, my attention was called, by Mr F. Darwin, to 

 the occurrence, on hermaphrodite plants of Origanum vulgare in 

 his garden, of occasional flowers having one, two, three, or even 

 all, of the stamens aborted. I found such flowers, on examination 

 of many plants, to be of fairly common occurrence. The corolla is 

 usually smaller than in the normal hermaphrodite flower, and 

 may even, especially in the case of the female flowers, be as small 

 as the corolla of a normal female flower (i.e. a flower on a female 

 plant). The aborted stamens are represented by small dark- 

 coloured bodies in the throat of the corolla, usually sessile, but in 

 some cases shortly stalked. 



