SCIENCE-GOSSIP. 



Si 



the gland at the base of the bract. Long before 

 the opening of the floral segments the globule 

 has reached its full dimensions of two or three 

 lines in diameter. It soon hardens on exposure to 

 the atmosphere, and has a high degree of viscidity 

 from its earliest appearance. Considerable force 

 must be exerted in expelling it from the tissues of 

 the plant. Mr. Darwin's explanation is that in 

 these cases the excretion is for the sake of getting 

 rid of superfluous matter during the chemical 

 changes which go on in the tissues of plants. But 

 as starch is necessary for storage, and plants 

 generally have no superfluity of the article, why 

 should the plant labour to form that which, in this 

 case, must be the wholly superfluous article of 

 nectar ? To get over this difficulty, Mr. Darwin 

 had already suggested that nectar was in the 

 earlier ages of plant-life always superfluous. That 

 insect life at first had no knowledge of its existence 

 or value, and that, on discovering it, insects and 

 flowers became gradually more correlated. 



So far as we can now see, these secretions 

 render the plant no service whatever in the great 

 battle of its life, and this Mr. Darwin frankly owns. 

 To him it is an act of excretion of useless matter. 

 To us who believe that individual life is not 

 wholly for itself, but that every act is of some use 

 in the general economy of nature, the new field 

 opened up is one of extreme interest. Observations 

 in this beautiful field are too limited to warrant 

 any general deduction as to the purpose of these 

 stem-bearing glands The object of this paper is 

 to draw the attention of those who may have 

 orchidaceous plants to a closer examination of their 

 structure, and to encourage a record of such 

 observations. 



Hybrids in Natcre. 



Our gardens abound with hybrid plants. 



Although the gardener's skill originates them, there 



seems little reason why they should not occur in 



nature. The plant desired to produce seed has its 



■:r opened by the hybridizer before it naturally 



expands; the anthers are removed before the 



pollen sacs are ruptured, insects are excluded, and 



the next day probably, when the stigma is recep- 



jn pollen is applied In this way 



Prom the ease with which 



hybrids are produced in this way ari • lief 



that hybridism in nature must be of frequent 



occurrence 



It is a matter of grave importance that we 

 decide how far this Ix.-h' , a 



peritxl not remote, it wrai a belief that 



i as a »fx.-< from the 



earliest epoch Win i,. r 



observation thai ted from 



•he ■ brio", it 



wo«: | ,,| 



hybrid origin. Thus Linnaean nomenclature 

 abounds in "hybrida" as a specific denomination, 

 If it can be shown that these are not hybrids, but 

 have been evolved from other species under some 

 regular law of development, the importance of the 

 question becomes apparent. 



We now accept the doctrine of evolution as 

 beyond discussion. Species do follow from other 

 species as the world advances ; but the old idea is 

 still so prevalent, that many botanists who accept 

 the facts of evolution in a general sense are very 

 apt to regard any unusual departure as a case 

 of hybridism. Our modern literature abounds in 

 such instances. Supposed hybrids are being 

 continually described as actual hybrids on no- 

 other ground than that they possess characters- 

 common to others already described. 



If nature intended hybridity to be one of her 

 handmaidens in the production of new forms," she 

 has strikingly failed. Let us take the oak as an- 

 illustration. When the male flowers are at a 

 certain stage, a slight jarring of a branch will 

 cause the pollen to float away in little clouds 

 discernible to the watchful eye. One may readily 

 conceive what an enormous quantity of pollen 

 must be carried from one tree to another by every 

 sudden breeze. In our woods there are rarely less 

 than two or three species in company. Not 

 infrequently there are more, and these are 

 usually blossoming all at one time. Hypotheti- 

 cally, one may argue that these gregarious 

 species must receive one another's pollen, 

 must cross fertilize, must result in a hybrid 

 progeny in which every separate characteristic 

 will be irretrievably lost. But the careful student 

 of nature knows that this is not so. The seed 

 collector goes into a wood which may contain 

 white oak, black oak, scarlet oak, red oak, chestnut 

 oak, swamp white oak, post oak, black-jack oak, 

 scrub oak, as he may do along the Wissahickon, 

 gather the acorns of each species under its 

 particular representative, and plant them with the 

 absolute certainty that they will be true to their 

 several parentages. This could not be if the 

 hypothetical proposition cited, of free inter- 

 pollination, were an actual fact. 



How, then are we to account for the striking 



deviations from typical forms which we occasionally 



see? I have long believed that form is the result 



of various degrees of rhythmic growth. It is the 



mechanical result of varying degrees ol energy. 



These results may be in, ii :1 | on a single tree. On 



the weaker branches of a white oak the leaves wll' 



be comparatively entire; on the Btronger shoots, 



, i rampant, thi leaves will be 



deeply lobed. In mulbi rrii thi i different es 



be well n 'i he leaves on branche - lull 



th vigour are lobed, bul « hen this enei 



pent, wholl) entin lea - ■ follow 



