18,2 The Ohio Naturalist. [Vol. X, No. 8, 



sulca, etc., was kept close to the window, where the sun had 

 access for an hour or two on clear mornings. In that, the plants 

 developed earlier, and at the present writing, several of them 

 are fully developed, unmistakable Spirodela polyrhiza, with 

 two disks several times the size of the bud, bright green, with 

 distinct nervation, several roots and with the inferior side 

 around the hilum purplish. On one of them, the bud is now 

 fading and withering. 



Thus the cycle is complete. The small bodies described were 

 seen developing on the Spirodela plants, in late summer and fall, 

 then detached or held only mechanically, surviving the winter 

 at the bottom, rising to the surface in spring (premature indoors), 

 producing new plants, and then dying. The observations are 

 complete so far as they go ; but more details and further investi- 

 gations will be in place. It has not been ascertained whether 

 one Spirodela disk produces only one bud or several, how early in 

 the season they are produced and eventually whether some of 

 them grow out into new plants in the same season ; also the micro- 

 scopic structure especially of the hilum when dormant and at the 

 time of sprouting will be of interest. The buds should also be 

 taken up from the bottom of ponds and pools in early spring 

 and their development observed. 



When the little bodies were first noticed, last fall, it was sup- 

 posed that they might be "winter-buds," having the function of 

 buds or bulbs, and the result sustained the diagnosis. Since the 

 plant is rarely found blossoming and fruiting these buds are evi- 

 dently the means of propagation of the species. But the term 

 "bud" is not adequate. They may be compared with the bulb- 

 lets of some Pteridophyta. Their significance is possibly nearest 

 to that of tubers, like those of the Dahlia and potato, but the fact 

 that they are provided with chlorophyl and stomata again sets 

 them apart. Their configuration is in accordance with the 

 simple structure of the plant itself. 



It may be mentioned that a Lcmna {trinervis Austin?) brought 

 in and kept with the Spirodela showed nothing of the kind des- 

 cribed; but it may have been overlooked; most of them died 

 earlier than the Spirodela. Lenina trisulca L. keeps well and 

 grows luxuriantly over winter, indoors, and is a very satisfactory 

 plant for small aquaria. 



New Philadelphia, Ohio, March 12, 1910. 



