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SCIENCE 



:N. S. Vol. XXVII. No. 682 



with which I was so familiar as to be able 

 to recognize alternations readily. Of the 

 various tests with this plant, one, which 

 had been treated with a solution of zinc 

 sulphate, gave seeds one of which produced 

 a plant, known to my associates and my- 

 self as "F. 206," which differed so 

 markedly from the parental form as to be 

 recognizable by a novice. This form has 

 been tested to the third generation, trans- 

 mits all of its characteristics fully, and 

 does not readily hybridize with the parent 

 even when grown so closely in contact with 

 it that the branches interlock. 



With this additional success, next nine 

 species in the genera Opimtia, Cereus, 

 Menizelia, Argemone, Nicotiana, Eschs- 

 choltzia and Pentstemon, which were 

 growing naturally in the vicinity of the 

 Desert Laboratory, were operated upon, us- 

 ing various solutions, inclusive of calcium 

 nitrate, potassium iodide, zinc sulphate, 

 and methyl-blue in various proportions 

 from 1 in 250 to 1-50,000 parts of distilled 

 water. Over a hundred thousand seeds 

 were harvested from the treated ovaries 

 and some were sowed in August, 1907. 

 Most of the species in question develop 

 slowly, and the seeds are difficult to 

 germinate under control. I am not pre- 

 pared, therefore, to make any definite an- 

 nouncement concerning the results, except 

 to say that among the seedlings of Cereus 

 are several which seem far from being 

 typical. 



The principal contribution to be made 

 at the present time bears rather upon the 

 mechanics of the action involved by this 

 treatment. The original results were dis- 

 cussed with the assumption that the in- 

 troduction of reagents into the ovary 

 would be followed b.y action on the egg. 

 In order to test this matter, solutions of 

 methyl-blue were injected in the same man- 

 ner as the other substances and examina- 

 tions were made at various times from a 



few minutes to a day later, for the purpose 

 of gaining some idea of the mechanical 

 behavior of the fluids. The facts obtained 

 from the great tree cactus, Cereus gigan- 

 teus, will best serve as an illustration. 



The ovaries of this plant are inferior 

 and one-celled, the cavity having a 

 capacity of about 2 c.c. The inner layer 

 seems to function especially as a conduc- 

 tive tissue, and from it the concrescent 

 funicular stalks arise, bearing the ana- 

 tropous ovules to the number of several 

 hundred, the whole offering exceptionally 

 favorable conditions for treatment of the 

 reproductive elements. 



The large flowers open early in the morn- 

 ing and attract a variety of small bees and 

 gnats, the former probably being instru- 

 mental in effecting pollination. If this is 

 accomplished and the temperature rises to 

 80° F. the flower closes at the end of the 

 day and falls off a day or two later. At 

 lower temperatures, the flowers may re- 

 open on a second or even a third day. The 

 style is 5 or 6 cm. in length and the pollen 

 tubes must traverse its length within ' 

 twenty-four hours and probably accom- 

 plish it in much shorter time. It was, 

 therefore, thought advisable to make in- 

 jections between 10 a.m. and 4 p.m. of the 

 day the flowers were open, or perhaps on 

 the previous day. 



Generally the needle of a charged 

 syringe was thrust diagonally downward 

 until the tip projected into the central 

 cavity, and the reagent forced in by the 

 pressure of the piston, as much as .5 c.c. 

 being introduced in some instances. The 

 use of this maximum amount would cause 

 a visible enlargement of the ovary, but 

 even in such cases the mucilaginous char- 

 acter of the tissues and the high turg-idity 

 would quickly close the wound when the 

 needle was withdrawn. With lesser 

 amounts and using the greatest care in 

 manipulation, the operation was followed 



