July 1, 1S70.] 



HARDWICKE'S SCI E N CE-GO S SIP. 



145 



ACCIDENTAL VAKIATIONS OF SEED-LEAVES. 



By ROBERT HOLLAND. 



ETER reading Carlyle's 

 pathetic lament,* that 

 there was no one 

 found to teach him 

 the first steps of Na- 

 tural Science in his 

 youth, it is pleasant 

 to turn over just one page, and 

 find the great writer's prophecy 

 already beginning to be fulfil- 

 led, and a master of Rugby 

 giving us an account of his bo- 

 tanical class. Let us hope that 

 the day is not far distant when 

 all other great schools will- 

 nay, must — follow the good ex- 

 ample set at Rugby. Let us 

 hail, too, the " one dissentient 

 voice" who'discovered the three 

 cotyledons where there ought only to have been two, 

 and hold out the hand to him as to a good friend 

 and fellow-worker in science ; not only because of 

 the merit of his discovery itself, but because he has 

 set much older workers than himself thinking about 

 these things. 



As soon as I had read Mr. Kitchener's remarks 

 about tricotyledonous exogens, I began to cast it 

 over in my mind whether I had not very frequently 

 seen these variations. I felt quite sure that I had 

 seen three seed-leaves, both in borage and in the 

 seedlings of sycamore ; and I fancied it was no un- 

 common occurrence in most kinds of plants. But 

 I came to the conclusion that the best way to decide 

 the matter was to go into my garden and inspect the 

 various kinds of seeds that were then coming up, 

 and see what information could be gleaned from 

 them. 



So I went there and then: and first, I looked 

 through a bed of young lettuces, and very soon 



* Science-Gossip, May, I870, p. 112. 



No. 67. 



found one with three cotyledons. Next, I hunted 

 through two beds of radishes, but here I was un- 

 successful ; still, I found amongst the radishes some 

 very curious examples, which have to be described 

 presently. Then I attacked the borage; but neither 

 here could I find any plants with three cotyledons ; 

 but I found a good many— perhaps half a dozen — 

 that varied in quite as curious and interesting a 

 way, for they had only one seed-leaf. In most in- 

 stances this variation was caused by the entire sup- 

 pression of one of the cotyledons; and then the one 

 that was developed became very much broader than 

 usual, being nearly orbicular, instead of oval, so as 

 to compensate, in some degree, as it were, by in- 

 creased size, for the loss of leaf-surface sustained 

 in the decreased number of cotyledons. In one 

 instance, however, the midrib of the cotyledon was 

 distinctly forked, showing it to have been formed 

 by the union of two imperfect leaves. The next 

 seed-bed was parsley, and here also I found a tri- 

 cotyledonous plant; then Escholtzia, with equal 

 success. Then I set my boys to work, and they 

 very soon brought me some sycamores, and they 

 have since brought me a good many very curious 

 instances of malformed seed-leaves ; in fact, I be- 

 lieve it would be almost impossible to search 

 through a garden iu springtime without finding a 

 great many of these curious and interesting varia- 

 tions. 



Then, as to their cause, Mr. Kitchener says, " 1 

 did not see any trace of a double plumule, or any 

 other suggestion of a double embryo." Neither 

 did I ; except, possibly, in one case, where the stem 

 of a three-leaved sycamore was considerably flat- 

 tened at the upper part ; but I do not thiuk this 

 arose at all from the junction of two embryos, 

 because there was no trace of a furrow along the 

 stem, or of duplication in the plumule. Still there 

 are plenty of instances of twin embryos in seeds. 

 They are the rule, and not the exception, iu mistle- 

 toe. We frequently find two kernels in a nut ; and 



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