442 
The Ohio Naturalist. 
[Vol. Ill, No. 8, 
5. Hoi.kertv, G. M. “ The Ovule and Embryo of Potamogeton natans.” 
Bot. Gaz., 31 : 339-346- 1901. 
6. Lyon, H. L. “ Observation on Embryogeny of Nelumbo.” Minn. 
Bot. Studies. 2 : 643-655. 1901. 
7. MurbECK, Sv. “Die Embryologie von Ruppia rostellata, Kongl, 
Svenska Vetenskaps.” Akademien Handlingar. Bandet 36 : No 
5- i9 02 - 
S. Schai fner, John H. “ The Embryo-sac of Alisma Plantago.” Bot. 
Gaz., 21 : 123-132. 1896. 
9. Schaffner, John H. “Tlie Life History of Sagittaria variabilis.” 
Bot. Gaz., 23 : 252-273. 1S97. 
10. Weigand, K. M. “Tlie Development of tlie Embryo-sac in some 
Monocotyledonous Plants.’’ Bot. Gaz., 30 : 25-47. 1900. 
11. Weigand, K. M. “Tlie Development of tlie Microsporangium and 
Microspores in Convallaria and Potamogeton.’’ Bot. Gaz., 28: 
328-359. 1S99. 
EXPLANATION OF FIGURES. 
For tlie drawings, a Leitz stand and a Bausch and Lomb camera lucida 
were used. For Figs. 7 and 16,' a No. 2 Leitz ocular and No. 7 Leitz objective 
were used ; for Fig. 9, a No. 8 Leitz ocular and No. 3 Leitz objective ; for 
Fig. 17, a No. 2 Leitz ocular and Bauch and Lomb objective; for the 
others a No. 6 Zeiss ocular and a No. 7 Leitz objective were used. The 
magnifications given are those of the original drawings, which in the plate 
are reduced to of their diameters. 
Archesporial cell, x 950. 
Sporocyte and tapetal cell, x 950. 
Megasporocyte and two tapetal cells, x 950. 
Three megasporas and two tapetal cells, x 950. 
Four megaspores and two tapetal cells, x 950. 
Two-celled embryo-sac with remains of megaspores. x 950. 
Eight-celled embryo- sac showing the egg apparatus, conjuga- 
tion of polar nuclei, and antepodals. x 630. 
Large lower endosperm nucleus and antipodals. x 950. 
Staminate flowers showing pollen-sacs and microsporocytes. 
x 230. 
Pollen grains, x 950. 
Three-celled embryo and persistent synergid. x 950. 
Five-celled embryo, x 950. 
Nine-celled embryo, x 950. 
Seventeen-celled embryo, x 950. 
Older embryo showing dermatogen. x 950. 
Embryo showing origin of cotyledon (r), plumule (v), radicle 
( d , e,f ). x 630. 
Nearly mature embryo showing growing point, cotyledon and 
radicle, x 450. 
Fig. 
1. 
Fig. 
2. 
Fig. 
3- 
Fig. 
4- 
Fig. 
5- 
Fig. 
6. 
Fig. 
7- 
Fig. 
8. 
Fig. 
9- 
Fig. 
10. 
Fig- 
1 1. 
Fig. 
12. 
Fig. 
13- 
Fig. 
id- 
Fig- 
15- 
Fig. 
16. 
Fig. 
i7- 
