2058 Journal of Applied Microscopy 



spore-mother-cell and the divisions in the germinating megaspore are described 

 in great detail. 



In Galtonia, the mother cell usually gives rise to a row of four potential meg- 

 aspores, but occasionally only two cells appear in the row, one of which may 

 germinate directly to form the embryosac, a transition between the condition in 

 Liliiim where the megaspore-mother-cell develops directly into the embryosac 

 and the condition where one of four megaspores produces the sac. In any case, 

 the first mitosis in the megaspore-mother-cell shows thS reduced number of 

 chromosomes. The second division in a form like Lilium corresponds in all 

 essential details with the second division in a form which is to have two or four 

 megaspores, and there is a similiar correspondence in the third divisions. In 

 Scilla, it is interesting to note that while the number of chromosomes in the 

 gametophyte is eight, the number in the sporophyte varies from eight to sixteen. 

 In Tu/ipa, at the first mitosis in the mother cell, each of the daughter nuclei 

 contains twelve chromosomes and in the two succeeding mitoses this number is 

 mantained at the micropylar end of the sac, but at the chalazal end the sporo- 

 phyte number may appear at the second division or the number may vary, fifteen, 

 sixteen and twenty-one having been counted. 



The writer believes that the new generation begins with the reduction divis- 

 ion, both in the embryosac-mother-cell and in the pollen-mother-cell, and he 

 has no doubt that the processes in ovule and in the microsporangia of Angios- 

 permo are homologous. The four potential megaspores correspond to the four 

 microspores (pollen grains) ; cases of two potential megaspores show a step 

 toward the further reduction which is found in forms like Liliutn. The fact 

 that the megaspores take the form of a row, is due to position, there being no 

 opportunity for early isolation and rounding off as in microsporangia. 



c. J. c. 



Caldwell, Otis W. A Laboratory Manual of Part I considers plants from the view- 

 Botany, Outlines and directions for Labora- • ^ r ^i • • • i j i 



tory and Field work in Botany in Secondary POl"' of their physiology and ecology, 



Schools. 8vo. pp. vii + 107. New York, " while Part II considers their structure 



D. Appleton and Co., 1002. 1 1 ^- a > 1 ... 



^^ ^ and evolution. A year s work is out- 



lined. The directions for securing material, the outlines for study and the sug- 

 gestive questions should prove useful to the busy teacher. c. j. c. 



,.,.,,, ^ , This booklet is intended as an intro- 



Nelsofl, Aven. An Analytical Key to Some of 



the Commoner Flowering Plants of the duction to a Study of a manual rather 

 Rocky Mouiuain Region. 8vo. pp. vii + 94. than as a substitute for one. The list 

 New York, D. Appleton and Co., 1902. 



includes the more useful laboratory 



material in the region from Montana to New Mexico with a somewhat variable 

 eastward and westward extension. In general, the sequence of families is that 

 given in Engler and Prantl's Die Natiirlicheji PJfatizenfamilien. c. j. C. 



Hegelmaier, F. Ueber einen neuen Fall von The writer finds that in about two- 

 habituellerPolyembryonie. Ber. d.deutsch. j^irds of the half ripe seeds of Eit- 

 bot. Gesell. 19: 488-499, 1901. "^ . 



phorbia dtilcis J acq. there is more than 



one embryo, the number ranging from two to nine. In the ripe seed the 

 number is smaller, usually two or three, and one of these considerably larger than 

 the others. The embryo which develops from the egg is the only one which has 

 a suspensor and is also the one which becomes the largest embryo in the ripe 

 seed. Of the other embryos, some come from synergids and some from the cells 

 of the nucellus. A large per cent, of the polyembryonic seeds is not capable of 

 germinating on account of the disorganization of the embryo. c. j. c. 



