Section IV, 1917 [71] Trans. R.S.C. 



The Origination of Ascidia under Quasi-Experimental Conditions} 



By Francis E. Lloyd, F.R.S.C. 



(Read May Meeting, 1917). 



Malformations of parts, especially in cultivated plants, are of 

 such general occurrence and so widely known that one would fain 

 seek justification for recurring to the subject in something more than 

 mere description of such malformations. In the present instance 

 this is found in the circumstance that unpremeditated conditions 

 which, it eventuated, resolved themselves into those of a fairly exact 

 experiment, have afforded evidence that the mechanical pressure 

 resulting from disharmonious growth can call forth abnormalities of 

 various degrees of departure from the norm culminating in perfect 

 ascidia, in a plant hitherto not observed so to behave. 



The conditions in question were procured as follow: A large 

 number of seedlings of the cotton-plant had been grown in small 

 (3 inch) pots with the intention of using them for experiment under 

 glass. While it happened that these plants did not serve their original 

 purpose, they were nevertheless kept alive for over a year in the same 

 pots, in which of course they soon became pot-bound. As a result 

 of this, and in spite of daily watering, the plants became dormant. 

 They could however be stimulated to grow from time to time by 

 higher temperatures and more abundant watering until they finally 

 settled down to a balance of activities which barely maintained them 

 alive. Nevertheless, occasional buds were found to develop, and short 

 lateral shoots were formed. After the lapse of a year, such shoots 

 bore leaves of highly abnormal form, and in some of which one or more 

 perfect ascidia appeared in place of the median and lateral lobes. 

 It must be noted that the leaves of these shoots are juvenile. The 

 earliest are simply cordate, and are followed by trilobate and these 

 at length by five lobed leaves. It appears significant that the abnor- 

 malities to be described arise particularly when the leaves are becoming 

 more differentiated, and it would seem that the tendency toward 

 forming ascidia is an abnormal expression of the attempt to form 

 separate lobes. 



^Digest in Science n.s. 42: 879. December 17, 1915. 



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