Miscellaneous. 



441 



[May, 1910. 



progeny which showed the greatest 

 development of that variation, a fixed 

 double form was at length reached. 



Another, instance of an interesting 

 "ever-sporting" variety was afforded by 

 the race of five-leaved Clovers which the 

 Professor had succeeded in establishing. 



The case of " mutants " in CEnothera 

 Lamarckiana. to which the lecturer next 

 referred, afforded an instance of not 

 one, but several new forms, arising 

 suddenly in one generation from seed of 

 one plant. About a dozen of these 

 "mutants" could be relied upon to 

 appear each season ; the number of 

 different "mutants "is, of course, not 

 unlimited, but the same novelties spring 

 from it almost every year, and in cases 

 where they can be got to produce seed 

 by self-pollination, they breed true. 



One of the most interesting of these 

 "mutants " is the dwarf form known as 

 nanella, which, though much shorter in 

 the stem than the type, bears flowers 

 quite as large and is, therefore, very 

 showy. This form appears in the pro- 

 portion of about 2 per cent, of the seed- 

 lings from Lamarckiana every year. 



Another "mutant" named lata has 

 weak stems, and much broader leaves of 

 a paler green colour than the type, and 

 with rounded tips, while a form known 

 as albida is also fairly common, and, 

 like others, may be distinguished from 

 the type even in the seedling stages ; it 

 has narrow, whitish leaves. Many other 

 mutants have occurred and usually re- 

 occur among the seedlings of Lamarc- 

 kiana every year. 



The Discussion. 

 Professor Percival raised the question 

 as to whether there was any periodicity 

 in the occurrence of the periods during 

 which mutations occur, suggesting that 

 perhaps every ninth, tenth, or twentieth 

 generation or so might see their recur- 

 rence in certain species. Mr. Diuery 

 also referred to this question, basing his 

 remarks upon his experience among the 

 many " mutants " which occur naturally 

 among British Ferns. Prof, de Vries 

 thought that perhaps fifty generations 

 might be nearer the period at which 

 mutation? might occur, but pointed out 

 that the question must be pursued for 

 a long period, in order that it be 

 answered. So far no answer could be 

 given. 



Mr. O. C. Hurst expressed his obli- 

 gations to the lecturer for his lucid 

 lecture, and emphasised the importance 

 of the facts Prof, de Vries had stated, 

 namely, first that "mutants" were 

 general variations which breed true so 

 56 



long as they are isolated, and, secondly, 

 they were of sudden occurrence com- 

 pletely developed. 



The Chairman, in conclusion, thanked 

 Prof, de Vries for the lecture, and ex- 

 pressed the hope that all who are in 

 any way employed in raising new varie- 

 ties of plants will keep careful records 

 of their work, for, in order that greater 

 knowledge of the laws that underlie 

 the causes of variation may be obtained; 

 there was abundant need for experi- 

 ments to "watch, wait and record." 



THE PHILADELPHIA MUSEUMS. 



(For the Season 1909-10.) 



The Philadelphia Museums continue to 

 offer to the schools of Philadelphia the 

 privilege of bringing classes to study 

 its collections from foreign countries 

 and to listen to lectures along the line 

 of their geographic work. 



Visits to the Museums are most profit- 

 able to the children after considerable 

 study of a country or region in the 

 school room. 



At a time selected by the teacher, a 

 class or grade may be brought to the 

 Museums where they will be given a 

 lecture on the subject selected from the 

 accompanying lists. 



Each lecture is profusely illustrated 

 by coloured lantern slides. The lectures 

 are adapted to the comprehension of the 

 children who attend, those to the lower 

 grades being given in very simple 

 language. 



At the close of the forty-five minute 

 lecture the class will be divided into 

 sections, and accompanied by guides, 

 will be shown the products, manu- 

 factures and materials which appertain 

 to the country or countries on which the 

 lecture has been given. 

 . The visiting classes should be restrict- 

 ed to not more than about one hundred 

 pupils. 



Dates for Visits. 

 It is necessary for tho?e who wish to 

 take advantage of these opportunities to 

 arrange for dates and to select subjects 

 in advance. If arrangements are made 

 over the telephone, Preston 4798, call 

 for the Curator, Mr. Chas. R. Toothaker. 

 If by letter, address the Philadelphia 

 Museums, 84th Street below Spruce 

 Street. 



Nearly all schools find it convenient 

 to visit the Museum in the afternoon, 

 arriving at about 2 p.m. If any other 

 time of day is more convenient, arrange- 

 ments can be made accordingly. 



